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Oil Pressure Connection

Posted By: nikothenomad

Oil Pressure Connection - February 24th 2015 2:40 pm

So, we are getting ready to hit the road again. I was finally tucking away all of the wiring I've been sorting through when I discovered a connector that looked like it should be together but it wasn't. A read of my FSM revealed that it was to tie the oil pressure gauge in with the oil light.

Although each have been working independently apparently someone had disconnected this link long before we received the van and I never realized it since it was tucked up tight behind the dash.

Anyway, I re-connected it and learned why it had been disconnected, it blinks constantly.

So... here's the thing. We've owned the van for at least four years now and best we know have not had a problem with oil pressure. Of course when I get a chance to test it I will but meanwhile...

Is there anything else that might could make that light blink constantly?

Posted By: Reed

Re: Oil Pressure Connection - February 24th 2015 4:46 pm

The oil pressure "idiot light" is a simple on-off switch system. When oil pressure falls below a certain point (I forget what the factory sending unit pressure point is. Something in the neighborhood of 8 PSI if I recall) the contacts in the sending unit close and the circuit is completed and the light in the dash comes on.

The light is not supposed to blink. It will blink if the oil pressure is right at the point where each pulse from the oil pump provides enough pressure to open the the ground in the sending unit temporarily but the oil pressure is so low that the contacts close again and the light comes on.

Does is blink at all RPMs? Does it blink when the engine is cold and first started up? Your engine actually needs only about 10 PSI oil pressure per 1000 rpm, so oil pressure of less than 10 PSI at can be perfectly fine.

You definitely want to verify your oil pressure with a mechanical gauge when you get a chance. You can get them cheap at auto parts stores. You might ave a fine motor but a failed sending unit.
Posted By: nikothenomad

Re: Oil Pressure Connection - February 24th 2015 5:04 pm

Thanks, Reed.

I do want to know the actual oil pressure and will grab a gauge at some point. Meanwhile, the pressure on our dash gauge has always been right at mid level or dropped a bit lower on a super warm day when we get to a stop light.

When I connected the wires to make the gauge and light work together and started the van (meaning it was cold) the light immediately was blinking even though the oil gauge itself showed its normal (midway) pressure reading.

Your theory of the pressure being right at the pulse point is interesting.

Also, I didn't let it run very long with the light connected since I wasn't sure what was happening. So, not sure if it changes with rmps or not.

Wondering if there is a way to test the sender?



Posted By: Reed

Re: Oil Pressure Connection - February 24th 2015 6:21 pm

Interesting. If you have the rare gauge and light combination (most vans had one or the other), my guess is that youhave a failing sending unit for the light. Not really a way to test the sender other than hooking up a mechanical oil pressure gauge and seeing the PSI the light comes on at.
Posted By: nikothenomad

Re: Oil Pressure Connection - February 24th 2015 6:31 pm

Well then, I guess I'll be getting a present this week :o)

Yes, we have the combination of the light and the gauge. I'd prefer the gauge to show the actual PSI but I'll deal with that at a later date.

For now, I simply want things working they way that they should be.

By the way, I'm thinking the sending unit is the bell'ish shaped part since it just has the one wire connector on top. Sort of confused as to what each part is.

Posted By: Reed

Re: Oil Pressure Connection - February 24th 2015 6:46 pm

THe big gold bell is the sending unit for the gauge. The sending unit for the light is a small black an silver flying saucer shaped thing. It is on the same T fitting as the guage sending unit, but it should have three male electrical terminals coming out of it. The choke (+) wire is one of the lines that attach to the idot light sending unit.
Posted By: nikothenomad

Re: Oil Pressure Connection - February 24th 2015 9:19 pm

Hmmm... I'm going to have to get in there and look again.
Posted By: Reed

Re: Oil Pressure Connection - February 24th 2015 9:20 pm

I will try and scan the pertinent pages out of my FSM.
Posted By: nikothenomad

Re: Oil Pressure Connection - February 24th 2015 11:08 pm

Thanks. I've got some info in my FSM but it isn't really that clear. I'll look at it again.

Been thinking that since I want to eventually install a gauge that actually displays the pressure reading why not just do that instead of buying a tester. Essentially same thing only two for one... unless I'm missing something.

Can't quite figure out though why the gauges all go up so high when the pressure is typically pretty low?

Posted By: Reed

Re: Oil Pressure Connection - February 24th 2015 11:30 pm

Oil pressure gauges are designed for a variety of engines and operating conditions. A freshly rebuilt or tight engine will have oi lpressures in the 50-60 PSI regularly. For example, about ten years ago I had the 351 that is currently in my 89 Ford van rebuilt. Immediately after the rebuild the engine had about 50 PSI of oil pressure hot or cold, regardless of RPM. Now after it has worn in a bit it has 55 PSI on cold startup and about 25 PSI at hot idle. The PSI goes back up to about 55 when I am cruising down the highway. If your engine gets more than about 60 PSI you have a problem somewhere. Safe operating range for oil pressure in a standard street driven engine is about 10-35 PSI hot.

The "tester" I am referring to is the same thing as an aftermarket gauge that you want to put in the gauge cluster. It is a mechanical oil pressure gauge (or electric, is you are up for buying the sending unit, too).

The sending units are pretty simple. Coming out of the block by the distributor is a hexagonal tube. Screwed into the tube will be the gold bell for the gauge and the sending unit for the idiot light. The idiot light sending unit has three wires- one for the gauge, one for power, and one for the choke. The FSM should have clear pictures of everything, including the wiring diagram.
Posted By: wrcsixeight

Re: Oil Pressure Connection - February 25th 2015 1:02 am

My Fuel injected '89 has both the oil light, and the OP gauge, and now, as well, a mechanical OP gauge. I believe both light and gauge were controlled by the same sender on mine.

While my oil light never came on engine running, I was noticing very low oil pressure on the stock gauge at hot idle. I was going to buy a tester, but then saw I could install a mechanical OP gauge for less money.

I put it here:[Linked Image]

BTW, those Stock fuse holders were so extremely oxidized that recently they were intermittently cutting out on the wiper motor and brake light circuits. The replacement fuse is for the blower motor. It originally burnt out before my ownership, and many aftermarket fuse holders have melted since, but this current 8 awg Maxifuse holder has proven problem free. The fuse is to be 30 amps, but this 20 amp one has not yet blown.

Cutting a hole in the dash there was a chore, as one is cutting through metal. Dremel and many a cut off wheel were required.

I now have a red LED light in the gauge. It is harder to see the orange needle, but not terribly so. The incandescent bulbs were too bright and distracting.

I 'T'd the line with commonly available 1/8" NPT plumbing fittings, so that my original gauge and light still work. This is what my OEm electrical OP sender looks like
[Linked Image]

I see RockAuto shows at least 4 different OP senders for an '88 with a 360.

The mechanical OP gauge is SOOOOo much better. One can see instant responses in OP with engine rpm. One can determine when the oil is as hot as it normally gets, and this is well behind the coolant temp during warm up, and one can see the differences in different grades of oil and even see lower readings near the end of an oil change interval as the oil shears to a slightly lighter grade or gets diluted with fuel.

Before I had a tach, on one X country journey my Lockup torque converter was kicking on and off at highway speeds very quickly and fairly smoothly, and the OP gauge revealed the higher rpms when it would kick out. It was a dirty and improperly adjusted brake light switch causing it to drop out and re engage on road irregularities.

My Mechanical OP gauge will read ~68PSI when cold at any rpm. This is the bypass relief setting. When hot the maximum pressure is 62PSI, and that occurs at nearly 3000 RPM with M1 0w-30 AFE oil. 62 PSI occurs at lower RPM's with thicker oils when hot. Whenever the oil pump is in bypass, there is more parasitic drag on the motor than need be. It is not Oil PSI keeping metal parts from grinding against each other, it is the film strength of the oil. The PSI relates to how quickly the oil is pumped through the engine.

There is very little correlation between the OEM gauge, and the mechanical gauge. It takes about 45 seconds of the same rpm for the OEM gauge to follow the general pressure, whereas the mechanical gauge responds instantly to engine rpm. The OEm gauge does not swing as wide either, and is a lazy stoned drunk in comparison and just as trustworthy.

My Mechanical gauge needle, with hot as it gets 0w-30 oil, will read 14PSI and bounce between 14 and 16 rapidly at 525 rpm. While my OP gauge goes upto 100 PSI, at never sees anything over 70, so that portion of the sweep, and below 10PSI is useless. Mine is a cheapo Equus gauge. Perhaps an Autometer's needle will swing further making it easier to read.

Do note that with mechanical OP gauges one is bringing a hollow tube of Hot oil into the back of the gauge and chafing and failure can be messy and dangerous. They give a plastic tube with the cheap gauges. One can use copper tubing instead for more peace of mind. I took extra steps to prevent chafing or kinking of the provided Plastic/Nylon hose in early 07 when I installed mine.

Remember that OP is not a more is better thing. It is an ' as long as the minimum recommend PSi is exceeded at such and such and RPM, all is still well' sort of thing.

If more OP was better, we should all run 85w-140 gear oil, which is about the thickness of that Lucas Oil stabilizer crap which one should only add when the engine is so worn it can no longer maintain adequate oil pressure with the normal, properly formulated motor oil.

Lucas has 0 additives, and dilutes the additives blended into the proper motor oil, and as such should not be used. Lucas also makes some motor oils get all foamy when pumped through the oil pump, and you do not want foamy oil pumped into the bearings. Foamy oil can however absorb sound and make the engine appear quieter, when in fact more engine wear is taking place from a compromised oil film strength because of the aeration. Lucas Oil Stabilizer, the used car salesman's best friend. Well marketed junk.
If one desires thicker oil, buy thicker oil, at least this oil will have the proper add pack of detergents, extreme pressure friction modifying and anti wear additives. Sorry for the off topic rant.

I'm guessing you got your distributor working well enough that you are confident enough to move on?
Posted By: nikothenomad

Re: Oil Pressure Connection - February 25th 2015 3:48 am

Reed and 68, that's some great information and definitely something to think about. I really didn't realize the whole oil coming in from a tube deal. Guess I need to read a bunch more before I make my decision.

68, yes... the van is firing up and driving beautifully and we are all ready to hit the road!

By the way... question about the gauge that is on the van currently (original gauge)... it has simply L to H with some tick marks in between. Curious, is there any standard for what each tick represents in psi? While it wouldn't be highly accurate it might would at least give me a bit of an idea until I could get all of this sorted which will most likely be a few months or more since we'll be travelin'.

Thanks all and I will be back to re-read and contemplate this info once we are packed and cruising.

Posted By: wrcsixeight

Re: Oil Pressure Connection - February 25th 2015 4:44 am

I would not fear the Oil tube for a mechanical OP gauge. You've got enough skills that routing it to be kink and chafe free will not be an issue.

My tube is clear, and I can see the oil darken as the mileage on the oil adds up, if I look at where it passes through the firewall grommett.

As far as the tick marks on the stock dash gauge, Mine has a range of just over the first hatch mark to just below the One hatch mark above the middle, and the range I've seen is 14PSI lowest and 68 PSI highest( only when cold) according to my real OP gauge. The same rpm has to be held for 45 seconds before the stock gauge reads highest or lowest and relates to the mechanical gauge.

Meaning if I were Idling at 525 rpm for 45 seconds hot, the mechanical op gauge would be in the 14 to 16 PSi range and the OEM gauge would read a smidge over the first hash mark. Light goes green and I bring it upto 3000 rpm, the mechanical gauge would go right upto 62 PSI within a second, and 45 seconds later at 3000 rpm the dash gauge would read as high as it ever does, A little bit over half way up the gauge.

I think I am still on the original sender though, and perhaps it is lazy/slow.

I am not sure how quickly aftermarket electrical oil pressure gauges respond to rpm, faster than the stock gauge, but I do not think they can be as fast as the mechanical gauge. My gauge was 15$ or so and very worth the piece of mind it gave me.
Posted By: Reed

Re: Oil Pressure Connection - February 25th 2015 4:29 pm

I run electric aftermarket oi lpressure gauges since i hate to think about a mechanical oil pressure gaguge springing a leak in my interior while cruising on the highway. Aftermarket electric oil pressure gauge rspond immediately to changes in oil pressure. Stock factory gauges are very slow to respond. I have never found a correlation betwen the lines on the Dodge oil pressure gauge and any specific PSI reading.

I have used cheap $20 electric oil pressure gauges that worked fine but in my 89 Ford van I run autometer ultralite gauges. I get them used on eBay when I can find a good deal on them. Large auto parts stores should stock cheap electric gauges.
Posted By: nikothenomad

Re: Oil Pressure Connection - February 26th 2015 2:45 am

Sweet. Thanks ya'll. We hit the road tomorrow so I'll have plenty of time to think over what kind of gauge I want as we slowly cross the country yet again.

By the way, 68, sounds like your oil pressure reads same on the original gauge as ours does.

Well, off to pack up and get ready to leave.

Posted By: nikothenomad

Re: Oil Pressure Connection - February 11th 2019 8:05 pm

Re-opening this because.... our stock OP gauge has been reading L or a hair above for a bit now even flying down the highway. So, I finally... (four years after this post) put a cheapo mechanical gauge in today and..... she's reading great in the 60 range when running, 45 - 40 idle operating temperature with the AC on. I'm pretty psyched because that seems good.

However, I don't have any actual reference numbers for what she should read as I can't find any in my FSM. But at least she isn't reading 0 which is what the stock gauge would indicate sometimes!

Loving that 30 year old oil pump.
Posted By: CatFish

Re: Oil Pressure Connection - February 11th 2019 8:24 pm

Looks like excellent oil pressure to me!! Yay Annie!! cool
Posted By: nikothenomad

Re: Oil Pressure Connection - February 11th 2019 8:42 pm

I know, right, CatFish! We were super psyched. I mean we've always had confidence that we got ourselves a good one but after 30 years there is always that little bit of doubt. So, we were super happy to see those numbers.
Posted By: Astrocreep66

Re: Oil Pressure Connection - February 11th 2019 11:39 pm

That is excellent pressure,bearings are in great shape.cool beans🚐
Posted By: jcd74

Re: Oil Pressure Connection - February 12th 2019 2:02 pm

The small 2 wire sender is for the fuel cut, the larger 1 wire male tab sender is for the gauge, I just did the same thing with my 89 g30, was freaking out about the oil pressure. I had removed the oil cooler because of bad oil lines, instantly turned the oil black in warm weather. Oil gets to hot and I have like 12 # low idle. when warm, 65 plus on cold start.
Posted By: nikothenomad

Re: Oil Pressure Connection - February 15th 2019 6:44 pm

Thanks, Astro... yes, she is holding at 62 on long drives and even when fully warm doesn't drop much below 40 so we are thrilled.

jcd... not sure what you are referring to?
Posted By: jcd74

Re: Oil Pressure Connection - February 15th 2019 11:20 pm

Sorry I started on page two, just went thru a pressure scare myself. Did the same got a cheap gauge to compare the stock gauge, went with the dash gauge instead (changed the sender), it was more responsive than the mechanical one. BTW I have a Chevy.
Posted By: wrcsixeight

Re: Oil Pressure Connection - February 15th 2019 11:20 pm

The rule of thumb, at least on small block chevy is 10PSI for every 1000 rpm minimum.

Keep in mind it is not the oil PSI separating metal parts, it is the oil film strength.

So which oils are you getting those readings?

My engine on cold start up goes right upto 68PSI

When hot the maximum I will see is 62PSI

These numbers are the what the bypass spring is letting oil go into bypass at.

Right now with Pennzoil Platinum 10w-30 with ~6k miles on it, at 2K rpm highway, 42 PSI
HOt idle when first exiting highway at stop sign/redlight is 20PSI@ 525 rpm.

Thicker oil weights would raise these numbers but not beyond 62 hot and 68 cold.

If I was always seeing 60+ PSI I would use thinner oil.

Oil PSI is not necessarily more is better, if it were then we should all run 80w-90 gear oil and be in bypass the whole time.

Oil PSI is like anything over a minimum amount per RPM is fine.

My stock gauge is laughable in accuracy and precision, When I see it low I completely disregard it and look at the mechanical gauge which shows healthy PSI for the rpm.

Oil PSI and Thick oil vs thin Oil arguements can go on Non stop.

Just use a good API rated oil and a good filter, and don't add any additives to it.

While Fram Filters have a long standing bad reputation, the Fram Ultra is a very well made filter, with very good efficiency and flow. I use the Fram Ultra XG8a and will be using it for 2 oil changes this time.

Id not use the other Fram models but they too are well beyond the cardboard endca internet brewhaha of yesteryear.

In fact the older Purolator white cans started having bad media tearing issues where a significant portion of oil in such a filter would pass through the filter, unfiltered.

I am not trying to save money on Oil, or Oil Filters, but 5 quarts of Pennzoil platinum at wally workd is ~25$ and a 9 dollar fram ultra cannot be beat, The only filters likely any better are AmSoil and ROyal purple, at 3 to 4x the price.
Posted By: Marcela

Re: Oil Pressure Connection - February 16th 2019 2:05 pm

Might want to consider if the engine is flat tappet, using an oil that was available prior to the roller engine era. IE something with zinc.
Posted By: nikothenomad

Re: Oil Pressure Connection - February 17th 2019 1:14 pm

jcd... thanks. got it now. I pretty much knew it was a faulty stock sender since it would seem unheard of that she could roll down the highway for hours while reading L or below L. As always (if you've seen any of my other work you'd know) i kept my stock sender and will clean it up to see if i can get it working and then put a T fitting on the set up at a later date so that i can play with comparing gauges like 68 did.

marcela... i'm still running 85% original parts so don't think the original 5.9 360 was a flat tappet idea but the oil i have always stuck with has the ratings / numbers listed that match what my fsm wanted used back in the day.

68... so here are some more specific numbers. It is still new to have actual numbers to watch for and we had gotten used to knowing that the stock gauge wasn't accurate so has taken me a few days to get a sense of them. when we first start up we see 70'ish cold... I still forget to get an exact number there but cold start is the highest we've seen so far. on the highway and steady driving she does not deviate from 62. the other day i remembered to glance at it after a good drive while sitting fully hot at a long red light (AC on) and she was at around 25. as soon as we started driving again she popped right back to 62.

as for oil and filters. I was a long time fram ocod user - don't remember which model. when that whole deal started being discussed i dissected the one we had been using and saw now problems but still at that time swapped to the purolator 30001. Since the 30001 had a change we switched again this last time and I can't for the life of me remember exactly which oil filter we got this time around but i think it was motorcraft. For oil i have always used the standard quaker state 10w30 that specifies it meets the numbers my fsm wanted back in the day MS 6395. I still run oil and filter changes way more frequently than recommended at 2500 - 3000 miles and do not use additives.

will also be swapping out electric temp gauge we got from summit that has not functioned well for the last year with a mechanical one in a few weeks. looking forward to see what readings we get on that.
Posted By: wrcsixeight

Re: Oil Pressure Connection - February 17th 2019 9:20 pm

The Fram OCOD issues were really overblown back when they were having issues with them, and the whole 'cardboard' endcaps thing is also been distorted by internet rumor. I would not fear the OCOD anymore, but for the same $$ there are better filters. The Fram Ultra is very well designed and made with very high efficiency wire backed media, I think it is 99% efficient at 20 microns and 80% efficient at 10 microns. For the 9$ price tag they cannot be beat, in my opinion.

The Purolators went downhill towards the end of the white can days, with uneven pleat spacing by the seam leading to tearing of the media nearer the baseplates. Motorcraft FL1a is/was made by purolator. Purolator has changed ownership lately and who makes what for whom is not something I really keep upto date on. I did like the thread end bypass on the FL-1a and when I opened up the one I used, it showed no evidence of tearing at the seam.

Regardig your 60psi oil pressure at highway speeds, I forgot you have a 3 speed 727, which likely runs close to 3K rpm at 65mph with 3.55:1 rear gears. Mine runs ~1975rpm at 65mph with Overdrive and lockup and 3:55's as I have the more delicate A500 or 42rh trasmission. Next time I am at 65mph an hot I will take it out of OD and see what PSI mine goes to in third, but in OD at 1975 rpm mine sits at 42 PSI as hot as it gets, and this number is also checked a bit more often as my OEM temp gauge has been reading higher than normal lately, but the Oil pressure gauge has not fluctuated from 42 PSI at 65mph, and if it were indeed running hotter the oil should be thinner and thus have less PSI.

The dashboard voltage limiter(5 volts) on mine started acting a bit funny and rather than spend 35+$ for a new one, I used a 8$ modern solid state voltage bucker to send 5v to the gauges, but I have not verified lately that this 5.00v I set it has not drifted in the last few years. Before going with this new voltage limiter the temp gauge on hot restart would shoot upto the H before settling midway, with the newer limiter it will only slowly rise after a hot restart.

Since I have not trusted my OEM coolant temp gauge for a while, and the Oil PSI is only somewhat reassuring that I am not running hotter than desirable, I have used thermal epoxy to adhere a K type thermocouple to my thermostat housing, and a few other areas, like my alternator. The k type is the same as provided with many digital multimeters, and I have a device which can display the readings of 4 Ktype thermocouples at once. The one on my T stat housing reads 180f +/- 2*f at highway speed, but when I slow to a red light at an offramp, it will quickly climp to 196f, but then just as quickly lower back to 194.5 and stay there, indicating the thermostat has opened enough to keep the intended 195f. This is reassuring as my OEM temp gauge might read normal or almost a full hatch mark above normal. I want to cover this area to protect it from windflow so as to get more accurate readings at highway speeds.
Seems modern manufactures thermostats, whether Stant superstats or Motorrad or Gates are all quite Junky. Mine seem slow to open fully on initial warm up, looking at the OEM gauge.

Obviously the airflow over the engine is responsible for the 180f reading at highway speeds and once stopped the flow from the fan is not enough to really reduce the temp reading and it more or less indicates true engine temperature.
Anyway i would certainly be much less comfortable ignoring the OEM gauge without the Oil PSI and the K type thermocouple on the t stat housing which indicate all is well, that the OEM temp gauge is not to be trusted.

I installed the Ktype on the T stat housing August of 2017 as it was reading high, but after a longer road trip it started reading normally again, until my recent cross country journey last November, when in Texas when it started reading high and I plugged in my 4 k type teperature gauge to see all was still well and as expected, which it was, which allowed me not to freak out about the higher than normal OEM gauge reading.

I cannot explain the inconsistent unexpected swings of the oem temp gauge, but Oh well.

As far as changing out the oil more frequently than 3K miles, the only way I would do that is if it was over a year since the last oil change, or the Oil smelled like gas from running too rich, or the Oil PSI read much lower than expected indicating the oil sheared to a lighter weight or perhaps an internal engine issue.

When one changes the oil, the fresh new detergents can strip off the ZDDP layers and other extreme pressure/antiwear additives that the previous oil has laid down over time with heat and pressure. If the engine is run hard right after an oil change, the new oil might possibly have stripped off these protective layers, and not yet had time to place its own down on the bearings/cam lobes, thus increasing engine wear.

So unless you know the oil is sheared or contaminated, or simply too old, changing it more frequently is NOT doing the engine any favors and could increase engine wear. Conventional oils of today( versus even 15 years ago) can easily go 5K miles and Synthetics 7500, but gasoline direct injected modern engines are having fuel dilution issues and manufacturers are recommending shorter oil change intervals that what the owners manuals originally stated.

I think I am about 5.5k Miles on this oil change since October 2018, and do not intend to change the Pennzoil Platinum sn+ 10w-30 until I am back in California, no less than 2600+ miles from now. In the ~5.5k miles I have driven this OCI. I have added 1 quart make up oil. Since wally world's 5qt jugs are inexpensve, I have been using Mobil 1 for the last 10+ years, and even though I never have cold start requirements, I was using Mobil1 0w-40 as it is such a good oil, the basestocks required to meet the 0w-xx specs needing to be a higher percentage of PAO ( group4) and esters( group5), rather than just Hydrocracked mineroils( group3). M1 0w-40 when I first used it made my engine much quieter over the previous M1 10w-40HM oil or the TDT 5w-40 I had been using previously, which in turn were quieter than the valvoline or castrol 10w-40s previous th that. Synthetics pretty much totally eliminated the lifter ticking on startup, warm or cold, which was enough for me to stay with Synthetics.

My latest Oil change Wal mart was out of M1 0w-40, and I was pretty much had decided to try something different anyway. On special I decided to go with eh pennzoil platinum SN+ 10w-30 @22.97 for a 5 quart jug and on startup a one particular annoying valvetrain type noise, that has been present for 50K miles diminished by 75% within 10 seconds of idling. And this quieter factor has remained at 5500+ miles later into the oil change. So needless to say I was surprised and very pleased, and will be sticking with This Oil for the forseeable future.

While it is hard to believe different oils can change the engine noise so significantly, the fact is that they do. Whether this noise equates to less engine wear cannot be determined without teardown style testing with all variables removed, but less noise is comforting. The PP 10w-30 is also showing slightly higher hot idle rpm (20) oil PSi than the M1 0w-40 did (18PSI) towards the end of the oil change interval , but slightly lower 2K rpm hot PSI. I do not really understand how that is functioning, unless the M1 is absorbing more engine heat at lower rpms. M1 0w-40 does use thinner basestocks than PP10w-30 which uses a gas to liquid basestock, but it has a higher 100C viscosity as well as HTHS viscosity due to the different types and amounts of viscosity index improvers.

The PP oil did go darker quicker but this can be expected when an oil known for high detergency is used in place of a different oil, and oil color is not really indicative of oil condition. Non detergent motor oils likely change color very little as the contaminants are sticking tothe insides of the engine rather than held in suspension by the motor oil.

Anyway QS 10w-30 is a known good oil. I'd not worry so much about original specs. My owners manual specifically says NOT to use 10w-40, because 10w-40s of that era were known to quickly shear/degrade into a sub 20 weight oil and not provide sufficient film strength to keep metal from touching metal. So that owners manual recommendation was relevant in 1989 but totally irrelevant with today's better viscosity index improvers/base stocks, and motor oils in general. Whether a 40w is required is debateable fo course, it could just lead to more drag from pumping losses and provide NO additional benefit, unless the engine were to overheat or run at elevated temperatures on the track, or the engine was prone to issues that are known to be resolved or mitigated with thicker oil, like piston slap which some newer GM engines are known for.

What is Good about 40 weight oils is they do NOT have to comply with lower ZDDP requirements of Xw-20 and Xw-30 weight oils, and ZDDP is good for flat tappet cams. Higher ZDDp on an oil burner can contaminate catalytic converters so they restrict the amount in SN rated oils, but not in the 40 weights or thicker. I forget the exact numbers but I think they are limited to no more than 900PPM of zinc or phosphorus, where about 1200 is said to be the ideal range for an oil with flat tappet cam lifters.

If you are looking for higher ZDDP oils then the diesel rated oils like shell Rotella have it, and are both diesel and gasoline rated and come in 10w-30 and 15w-40 and 20w-50.

Since ZDDp has been limited in 20 and 30 weight oils in the SN rating they have moved onto other additives, like Moly amd Boron and even titanium to replace the ZDDP as an antiwear/extreme pressure additive, but ZDDp is also an Antioxidant and many say that these newer AW and EP additives cannot replace it, especially in flat tappett cams.

As to whether your 1988 LA 360 has a roller cam, this Allpar site seems to indicate the 360 did not get the roller cam until 1989 while the 318 got the roller cam starting in 85, in trucks/vans. I could be reading it wrong though.

https://www.allpar.com/mopar/318.html

Anyway I am no tribologist, but I am not an 'Oil is Oil' type of guy. There are significant differences between brands formuations and weights, Whether these differences will make any difference in engine longevity is highly debateable. For me I want a Quiet oil, that is not going to easily shear to too thin a viscosity, keep my engine internals free of varnish and sludge, and can fight acidity for at least 10K miles in 6 months, or 2K miles in 14 months.

I did have a few sub 20f Starts at high altitude with PP 10w-30SN+ oil on my cross country journey and the engine had Zero Issues starting. It did stall when i put it into reverse though even with symthetic ATF+4.

Another thing about Synthetic oils, since they are likely to clean better, they can strip the gunk which was preventing oil from leaking past old gaskets and seals. So while Synthetics might 'reveal' oil leaks, they will not cause oil leaks, but the result is the same, and High mileage Synthetic oils might be enough to prevent revealing these leaks.

Really interms of wear, Modern Synthetics do no better than modern conventional/mineral oils, what they can do is last much longer before requiring to be changed and have much better cold flow characteristics for those who might be starting their engines in sub 0f.

I have NO fear of pushng the PP 10w-30 7500+ miles of mostly highway driving, which will allow me to change it once I return to California in a month or so, but if I were using conventional I would be stressed at pushing it that long, and likely be changing it before the trip. Doing so in my parents driveways is technically not allowed by the HOA, so I'd really have to go somewhere else to do it, or Pay someone else to do it, and I trust no Iffy lube joint to not strip my oil pan, or use a good oil of the proper viscosity and use a good filter as well. So The somewhat higher priced Synthetic is not only peace of mind, but also saving me money in the long run and running quieter too.
Posted By: nikothenomad

Re: Oil Pressure Connection - February 18th 2019 11:42 pm

68.... Yeah, thanks. I had heard that the Fram OCOD issue never really held up and my dissection showed a perfectly good filter. Still, I was happy for a change and enjoyed the 30001 for a good while until this last change when I couldn't find any leftovers on the shelves and had to go to Motorcraft. At some point I may look into the Fram Ultra.

Yes, we have the A727 tranny. We still don't have a tach so I have no idea of rpms yet. It's on the list for 'someday' though.

As far as you looking at your PSI at 65 it would be better for me if you did it a 55. We are very rarely found above 55.

You had mentioned the k type thermocouples that you put around your engine. We have one that goes with our multimeter and have utilized it as a comparison in figures we were compiling for various parts of the engine at one point. We compared those with an IR temp gun and a cooking thermometer. I haven't tried attaching them to anything while driving yet. I look forward to seeing what goes on with the mechanical temp gauge as we've had little to no luck with the electrical ones and I haven't been in the mood to do anything with the dash. Everything we've shot the temp gun at has appeared o.k. so I'm pretty sure we are but still would be nice to see some accurate numbers if we can.

Whether I fully change the oil at 3K or not is pretty much mute at this point (I believe) because we are having to put a quart in about every 500 miles so that's 5 new quarts in around the same mileage. I do run her rich but don't smell much fuel in the oil. Mostly get that exhaust smell in the oil is all. The consistency between my fingers feels good and not too diluted (not that it is an accurate test but it does indicate that things are at least not horrible).

One of these days I'll get less lazy with rich running at low altitudes but for now I just leave her because she runs better at high altitudes when I have her set rich. We'll be heading back up to 8000' in a few months so won't bother at this point. Maybe when we come back down in the Fall I'll play with it a bit.

I'll keep the Pennzoil Platinum in mind if I ever decided to switch from the QS. Been happy with the QS for now and don't have any knocks or pings or anything to quiet down at this point. But it is really interesting how you can notice a difference in the quietness between different oils. Something to think about for sure.

So, you are still in the FLAt lands with us? We take off in March but have been enjoying the beautiful weather. Hope you are enjoying your visit with your folks.

Cheers
Posted By: wrcsixeight

Re: Oil Pressure Connection - February 19th 2019 2:03 am

Yep still in Florida. Dad had knee replacement surgery a week ago. So I'll stick around until I'm sure i cant be helpful anymore.
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