Low oil pressure

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magnummopar said:
Good thing I have never seen a Taurus, Hundai, Toyota Tercel, Mazda 2200, anything Mitsubishi, Neon, Civic, etc. You are correct, I am just making it up to look like a dumb ***. I have never worked on cars before so I dont know ****.

OP go ahead and put 10w30 in it, drive it hard and if it eats itself you can blame the "expert" advise you got from guys that might be a plumber, waiter or maybe a gas station attendant. I certainly havent seen anybody claiming to be a professional mechanic respond. I even asked but got no answer. Its pretty easy to be an arm chair quarterback!

Anybody else with with a shop or professional experience care to chime in?

At least now you know what oil to run in your 5 cyl GM, Honda or Blazer :D
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You said it, not me. Still nothing to back up your claim,but quick to dismiss everyone else. Yeah, some stuff can crap out early, and it did back then too. Most people today don't even give a crap to change the oil even if the dash dings after it's 7k-12k oil change interval algorithm, which is likely why you're seeing them wear out. Any type of reasonable maintenance they go forever.

I've had engines with low oil pressure, which were weirdly all small block mopars. Every one had either sludged up pickups (from previous owner lack of maintenance), a failed oil pump screen sucked into the tube, or eroded cam bearings, usually followed by worn rod bearings. At some point it's gonna have to come apart if you care about it at all, thick oil or not. You can run it loose but it won't last forever. Let's say he gets 20 at hot idle on 20W-50 when its 40 degrees outside, a good avg temp for this time a year in MO. To me that's still time to take it apart if you want it to live a long time. It may come back just by swapping the filter away from a fram orange can. Wouldn't be the first time I've seen it.

Also, is he experiencing a spike in pressure at cruise when you let off the throttle? A sure sign of worn bearings.

FWIW: the '70 Service manual recommends 10W-30 as well for general use. 20W-40 in temps "consistently above 32 F" and says you can use 20W-50 in "racing environments"

The oil from today provides far better protection for bearings at least (maybe not flat tappet cams) than oils of when these cars were made.

"Professional shop experience" which has a pretty wide definition doesn't make you an expert on oil either. Whatever though.
 
Wow, seems like I opened up a can of worms here, lol. I love this forum because everyone is always eager to help the fellow mopar nut. Really good views on this, but let me clear up a few things. This 340 was built for the track, so I think saying it was built with looser tolerances is probably pretty accurate. Just from driving it on the street and having some fun I can say it's probably right around the 400hp mark at the crank. That being said, and after seeing how clean the bores are....I'd say it doesn't have much wear. Which again leads me to believe it was built with looser tolerances. It does get pretty cold in southeast Missouri, so not really driving it much at the moment, but it does get fired up once a week. So going off of some of the posters here I think I will just swap the filter, bump up to some 10w40, check the old oil, and if there's no metal in it I will run it as is. If I get any more reduction in pressure I'll be changing out the oil pump. Also, I've always ran royal purple in my stuff, and will probably stick with it unless anyone has good insight why not to? Thanks to all the posters...you guys are great.
 
Three pages of entertainment and it didn't cost me a dime! Back in the early 70's when I worked at a parts store ,we had three different brand oil filters cut open for the customers to compare construction, a Fram ,a AC Delco filter and a Motorcraft. Even back then the Fram had cardboard ends and had the fewest non consistent spaced pleats in the filter media. The Motorcraft was actually the highest quality looking filter. I will throw in my opinion on 10 PSI at running temp. If a new filter such as a Wix and a quality high zinc oil such as Lucas 10-30 Hot Rod oil doesn't improve on the oil pressure numbers, I would pull it out and go through the engine.
 
Going off the original post, and the question. You've stated that the motor has lost oil pressure since when you first got it and now. That's not normal, period. You've either got an oil pump that is failing, or bearings that are failing, or both. I personally wouldn't be comfortable with the situation, and would seriously consider pulling the motor and checking your bearing clearances. Buying a used motor, I would have plasti-gauged #5 and #7 rod journals at a minimum, and the main bearings before installing.
 
middleagecrisis said:
Going off the original post, and the question. You've stated that the motor has lost oil pressure since when you first got it and now. That's not normal, period. You've either got an oil pump that is failing, or bearings that are failing, or both. I personally wouldn't be comfortable with the situation, and would seriously consider pulling the motor and checking your bearing clearances. Buying a used motor, I would have plasti-gauged #5 and #7 rod journals at a minimum, and the main bearings before installing.
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This is why I recommended the oil and filter change. Perhaps the filter media is trying to collapse or it is stopping up. Would be cheaper than tearing it apart right off the bat.
 
Mopar Tim said:
I use Mobile 1 20/50 in all my old cars. 67 440 GTS Dart, 66 426 HEMI charger, and my 66 273 Charger Dart, still being worked on. I Built all of my cars. Just had machine work done, BUT I assembled all myself. Dont need to own a shop to know what is what. But I did turn wrenches at a GM dealer.
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Be careful, according to some here, if you start your cars with 20w50, it will blow up your engines
 
This is off the original topic: If I can ask a question on the Mobil 1 20W50, Mopar Tim, is this the stuff advertised for Motorcycle V-twins? I don't see any 20W50 Mobil 1 that they list for auto use. Not sure if it makes an difference or if there are any moto-specific additives in it. It sure has a healthy zinc level at 1750 ppm.
 
nm9stheham said:
This is off the original topic: If I can ask a question on the Mobil 1 20W50, Mopar Tim, is this the stuff advertised for Motorcycle V-twins? I don't see any 20W50 Mobil 1 that they list for auto use. Not sure if it makes an difference or if there are any moto-specific additives in it. It sure has a healthy zinc level at 1750 ppm.
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This one https://mobiloil.com/en/motor-oils/mobil-1/mobil-1-v-twin-motorcycle-oil High Zinc, Oil is Oil, just because it says motorcycle oil, no biggie.
 
Thanks; I asked because my son and I have been looking at different synthetics for his new 340 after some miles are put on it. I passed this one up because the product guide mentions additives for moto clutches, but I'll look into it more for summer use. It IS rated SJ so that seems good.

One thing I have noticed in using Mobil 1 products for a loooong time is that they seem to consistently be thinner at cold temps than other oils of the same viscosity rating, and looking at the 'pour point' shows this; this product has a -42C pour point as opposed to a -24C pour point for Valvoline VR1 20W50 and -27C pour point for Brad Penn 20W50. Another full synthetic shows -45C pour point for 2 Redline 20W50 synthetics (ester based).

IMO, one thing that is helping you use 20W50 year round is your location in southern CA, near San Diego. So your good experience is for a warm climate and is likely not as applicable to cold climate use of 20W50. Redline recommends not using their 20W50 at low temps at around -5F and below.
 
g49bridges said:
Wow, seems like I opened up a can of worms here, lol. I love this forum because everyone is always eager to help the fellow mopar nut. Really good views on this, but let me clear up a few things. This 340 was built for the track, so I think saying it was built with looser tolerances is probably pretty accurate.
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Cans o' worms are a specialty here! LOL It sounds like you have ID'd a possible reason for the pressures to be a bit lower. Good that you are being proactive on this, IMO. Can't offer any insight on RP as I never have run it; but I can't find any published numbers on the ZDDP levels; supposedly the HPS versions have more ZDDP, per their advertising claims, but I don't know quantitively what that means.
 
IMO, one thing that is helping you use 20W50 year round is your location in southern CA, near San Diego. So your good experience is for a warm climate and is likely not as applicable to cold climate use of 20W50. Redline recommends not using their 20W50 at low temps at around -5F and below.
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All true. I did have my Charger in Indiana a few years ago, yes I drove it there. It did get cold, snowing and Ice, and I kept the 20/50 oil in it. If I was to stay there, I would have switched it out. I did not drive it much in the snow, I was worried about the salt and rust.
 
g49bridges said:
Dropped it in my duster and when it starts cold the oil pressure was at about 50lbs, and then 25 when it warmed up. Now it's dropped to 40 cold, 18 when it warms up to 180. When you put it in gear it drops to 10 lbs, but comes back up to 40 lbs when its running at 2000 rpm. No noise in the top end at all.
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That's concerning.

I agree with RRR, try a new filter then go from there. It doesn't get much easier than changing the filter. Pulling the pan in the car isn't fun but it's easier than pulling the engine, IMO. If it gets worse that'd be the next step i'd take. Plasti gauge the bearings and check for wear, if everything looks fine then your oil pump might be takin' a dive on ya. There's only so many things that affect oil pressure.

Hopefully it's an easy fix for you and then you can get back to enjoying that 340. :burnout:
 
BlueDream said:
That's concerning.

I agree with RRR, try a new filter then go from there. It doesn't get much easier than changing the filter. Pulling the pan in the car isn't fun but it's easier than pulling the engine, IMO. If it gets worse that'd be the next step i'd take. Plasti gauge the bearings and check for wear, if everything looks fine then your oil pump might be takin' a dive on ya. There's only so many things that affect oil pressure.

Hopefully it's an easy fix for you and then you can get back to enjoying that 340. :burnout:
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It maybe a case of the oil thinning out from use and being slightly diluted from water and fuel. It could be time for an oil change. How many miles and start ups warm ups are on the oil? My 340 always had at least 20psi at hot idle oil pressure. I was using 5w40 rottella t6 or mobil 1 20w50.
 
magnummopar said:
Good thing I have never seen a Taurus, Hundai, Toyota Tercel, Mazda 2200, anything Mitsubishi, Neon, Civic, etc. You are correct, I am just making it up to look like a dumb ***. I have never worked on cars before so I dont know ****.

OP go ahead and put 10w30 in it, drive it hard and if it eats itself you can blame the "expert" advise you got from guys that might be a plumber, waiter or maybe a gas station attendant. I certainly havent seen anybody claiming to be a professional mechanic respond. I even asked but got no answer. Its pretty easy to be an arm chair quarterback!

Anybody else with with a shop or professional experience care to chime in?

At least now you know what oil to run in your 5 cyl GM, Honda or Blazer :D
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I am a professional auto technician. 25 plus years in the industry. I have been a Chrysler tech for 18 of those years.

While a manual may say 10 psi hot idle in gear is acceptable, I feel I is a sure sign of either excessive wear or a terminally failed component. The fact that pressure slowly rises when the engine is reved up tells me there is something wrong and it should be taken apart before it takes itself apart. If the oil pressure sprang to 40 or 50 psi when reved I would be less concerned and attribute the problem to worn bearings but not terminal.
 
340dartley said:
I am a professional auto technician. 25 plus years in the industry. I have been a Chrysler tech for 18 of those years.

While a manual may say 10 psi hot idle in gear is acceptable, I feel I is a sure sign of either excessive wear or a terminally failed component. The fact that pressure slowly rises when the engine is reved up tells me there is something wrong and it should be taken apart before it takes itself apart. If the oil pressure sprang to 40 or 50 psi when reved I would be less concerned and attribute the problem to worn bearings but not terminal.
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Thank you, I agree 100%. My last 17 years are Magnum only, building and swapping. I also thought about the oil gallery plugs being drilled like some of the old LA race build books used to recommend. I think OP said something about possible circle track use prior to taking ownership. That was theory behind 20w50 test with mopar filter. Apparently not a very popular theory with the reading comprehension challenged.
 
Magnum motors will be no different than any LA engine for the sake of this discussion so your Magnum experience is valid. As far as running 20w50 in a small mopar or any engine in a warm climate, you will not hurt anything. Engines with with variable valve timing like the 3.6 pentastar or multi displacement such as the late model hemp require the thin oil to operate their solenoids and cam phasers. They will not be damaged by thicker oil they just won't function correctly and will set check engine lights.

To the OP, remove the oil pan and inspect your bottom end. I find it easier to remove the engine to do this on anold A body. I suspect you will find a spun rod bearing. Good Luck.
 
340dartley said:
Magnum motors will be no different than any LA engine for the sake of this discussion so your Magnum experience is valid. As far as running 20w50 in a small mopar or any engine in a warm climate, you will not hurt anything. Engines with with variable valve timing like the 3.6 pentastar or multi displacement such as the late model hemp require the thin oil to operate their solenoids and cam phasers. They will not be damaged by thicker oil they just won't function correctly and will set check engine lights.

To the OP, remove the oil pan and inspect your bottom end. I find it easier to remove the engine to do this on anold A body. I suspect you will find a spun rod bearing. Good Luck.
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Thank you!
The sewing machine oil always makes me cringe when I pour it in the Audi turbo. Pours just like water....never understood how it can keep the rods from eating the crank when it starts to pour on the boost. 275 hp from teener, low stress, from 1.8L serious stress. Actually I do understand how, but my insecurity makes me so nervous I almost wet myself:D
 
magnummopar said:
Thank you!
The sewing machine oil always makes me cringe when I pour it in the Audi turbo. Pours just like water....never understood how it can keep the rods from eating the crank when it starts to pour on the boost. 275 hp from teener, low stress, from 1.8L serious stress. Actually I do understand how, but my insecurity makes me so nervous I almost wet myself:D
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----------DAM, this place is entertaining !!!!! anyone remember phillips 66 20w40 troparctic ? used to run it in my 68 383 form S barracuda when it was brand new, back in the day, loved it ! :coffee2:
 
Here's a copy of the oil weight chart that has appeared in Mopar Factory Service Manuals since time immemorial:
 

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Yep, I must be killing my engine... I have a 215k mile 1993 Chebby K2500 that has always used 5w30. I recently switched to 10w30 a few months ago.

But anyways, you were told to start another thread, but you keep scratchin'. Please take the sound advice given and stop hijacking this thread by arguing for the sake of arguing.

*Edit* Forgot my wife's 2007 Ferd Escape with 150k and still running 5w20. Still getting 25-27 mpg on the freeway.
 
FSM minimum limits have very little to do with an engine that's going to get romped on. Maybe it's the cynic in me, but seems more like cryco getting engines through the warranty period. Buying a used engine is always a crap shoot with whatever accompanying story. Like others on this thread I'd check the mains if it turns out it's not a stuck bypass.
 
Tantibus-74 said:
Yep, I must be killing my engine... I have a 215k mile 1993 Chebby K2500 that has always used 5w30. I recently switched to 10w30 a few months ago.

But anyways, you were told to start another thread, but you keep scratchin'. Please take the sound advice given and stop hijacking this thread by arguing for the sake of arguing.

*Edit* Forgot my wife's 2007 Ferd Escape with 150k and still running 5w20. Still getting 25-27 mpg on the freeway.
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I believe you might have misunderstood my point, I never said all new engines die early, I just said many newer engines dont last. I also didnt discuss causes like lack of maintenance, freeway miles vs short trip miles or good/poor design. I think we can all agree that the GM V8 is a long lasting engine as are many others, there are also lots of very short lived engines out there. I am glad the posters here are doing proper maintenance and it seems to be paying off with what might be considered higher than norm miles.
I will say that with the thinner oils, you have to be more up on timely changes as all oil looses viscosity as it breaks down(another can o worms). In other words, if you dont change your 0w20 or 5w30 on time, its less forgiving than say for example 10w40. This could be a reason for early failures, I am not sure what is causing it but keep doing frequent changes, it seems to be working well for you and it does for me. Also, dont forget, OP has an OLD engine which is somewhat different than newer stuff, although not much in terms of v8 GM.

I really dont want to argue about oil, I was simply OFFERING a way for OP to determine if anything is wrong with his engine for $25 without pulling it from car. Putting 20W50 in an OLD possibly worn or sloppy engine with new filter will eliminate possibility of bad fram and by watching what changes on gauge, get a better idea of bad bearing, oil pump, plugs drilled for racing(it was a "track" engine) or what ever is causing what SOME agree is probably not enough oil pressure for a 340 driven on the street and certainly not enough for hard use(another opinion).
I was trying to help OP not loose his engine due to what I CONSIDER really bad advise and I believe helping the OP is what the real purpose of this thread is.
 
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