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Oh NO .. another oil question


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Just changed my oil  to Rotilla  15-40 wt.oil ( states for Diesel engines) in my 1941 Buick 248 CI straight eight.  Original with 36,000 miles.   I didn't see any Rotilla this  wt. for gasoline engines.    As it turns out my oil pressure is running like 58 almost to maximum full gauge reading at highway speed. I think prior to this oil change it would be around 48 to 50.  Is this harmful to my engine?   I've read  in the past here about Rotilla users being pleased  but maybe they're using  for gas engines.  Nothing unusual seems to be going on that I can hear or see.  Your thoughts?  

Wayne B.

 

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Look on the Rotella bottle or jug and check the API rating. Rotella has for years carried both C (compression ignition, Diesel) and S (spark ignition) ratings, so it should be fine for your Buick Eight.

 

I think the pressure increase is due to the 40 weight rating. You can get 30 weight and 10w30 Rotella but most places only carry 15w40 as that's a commonly used Diesel rating.

 

Worst case is extra stress on an 80 year old gage, but I don't see any issues otherwise. What weight oil were you using before?

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Oil pressure is regulated by a spring loaded valve that dumps excess oil back to the crankcase, sometimes by way of the oil filter. What does your owner's manual or shop manual say is normal oil pressure? It seems high to me. Check by putting a mechanical gauge on the engine, also could the oil filter be clogged?

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Since we're on the subject of oil (again) What would be a good oil that has high zinc?  I'm currently using Valvoline VR1 racing oil, but i'm not sure that it contains the proper properties for proper expansion of rubber seals.  I'm looking at Rotella too, but the 30wt seems to be just for diesel engines.  I don't see the S identifier listed.  Suggestions?

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Oil better than water for lubrication. Any modern oil on the shelf is better than what they used in our antique vehicles, at least up into the 50s, when Zinc was added to oil.

 

On too high oil pressure, I've seen it!😲 Saw a new Corvair oil filter swell up like a balloon and spit the gasket out (put on as the one on the engine was also expanded 😉  ).  Yep, the pressure regulator piston was stuck in the bore. I cleaned it up and all was well.

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Interesting. Purolator got its start in 1923 but the interweb says "The first use of a full flow oil filter on mass production vehicles occurred in 1946."

 

Also an interesting thought. First heard Richard Rawlings say "Interweb" a few years ago but expect it is accurate. Many schools now teach with Chromebooks and they are mostly web based devices (good for people who do not like computers and can't afford Apples). Very good for Zoom.

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Another thought- if engine has an oil filter, did you use a different brand cartridge from what you'd used before when you put the Rotella in? Though on a bypass filter system you wouldn't think filter would greatly affect oil pressure.

 

I think it's generally accepted now that WIX, NAPA Gold and Baldwin are the better quality commonly available filters.

 

Padgett, that's interesting about high oil pressure eroding bearings.

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Was in the green sheets that Vince Piggins used to send to racers. Think it later became a book.

Something is niggling that Pratt and Whitney had an erosion problem in afterburning gas turbine engines back in the '70s.

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I'm surprised no one has mentioned synthetics. Although I currently don't run a syntetic oil, I'm convinced they are a better lubricant based on the results of some friends that use it.  I was considering switching my '39 LaSalle (V8 flathead "Cadillac" engine) over to a brand name full synthetic (maybe 5W-20) after I finish breaking in the engine.  I have about 1200 miles on it using 10w30 VR1 so, maybe another 1000 miles. I run just a bit high on oil pressure too ~50 psi driving at 60 mph.

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2 minutes ago, Stude Light said:

I'm surprised no one has mentioned synthetics. Although I currently don't run a syntetic oil, I'm convinced they are a better lubricant based on the results of some friends that use it.  I was considering switching my '39 LaSalle (V8 flathead "Cadillac" engine) over to a brand name full synthetic (maybe 5W-20) after I finish breaking in the engine.  I have about 1200 miles on it using 10w30 VR1 so, maybe another 1000 miles. I run just a bit high on oil pressure too ~50 psi driving at 60 mph.

 

 

Synthetic is fine.......I think I would go at least 5000 miles before the switch over.

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OP has an original 36000 mile engine. I wouldn't even consider putting a synthetic oil in it after 79 years of using what may or may not have been the best quality oil at the time. After a rebuild, yes.

 

If the higher pressure unsettles you, change the oil again with a different brand or weight and see if pressure drops back to what was normal before.

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I only use synthetics anymore, mostly High Mileage (more additives) 10W-30 for American Cars and 0W-40 for the two SLKs. With an older car I'd drop in a quart of ATF for a few hundred miles before changing oil (and filter if you have one) to thoroughly clean the innards first.

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13 hours ago, padgett said:

Purolator got its start in 1923 but the interweb says "The first use of a full flow oil filter on mass production vehicles occurred in 1946."

That's because they only used bypass or partial flow filtering between 1923 and 1946. The Chevrolet Stove Bolt six had partial flow its whole life, through the last of them in 1962.😉

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On 10/16/2020 at 2:29 PM, Stude Light said:

I'm surprised no one has mentioned synthetics. Although I currently don't run a syntetic oil, I'm convinced they are a better lubricant based on the results of some friends that use it.  I was considering switching my '39 LaSalle (V8 flathead "Cadillac" engine) over to a brand name full synthetic (maybe 5W-20) after I finish breaking in the engine.  I have about 1200 miles on it using 10w30 VR1 so, maybe another 1000 miles. I run just a bit high on oil pressure too ~50 psi driving at 60 mph.

i'm a little confused about synthetics. back in the 1970's, a rep. from mobil came to the olds shop where i was shop forman and told me only use synthetic oil in a new cae, not in a car with miles on it.i guess he was telling me the truth, since his job was to sell more oil. it would appear that at some point, all of that changed. i'm gonna stay old school on that and used non synthetic oil. i have my reasons, when firestone changed the oil in my wife's 1999 firebird (3.8) it went thru 3 quarts in a month. changed it back to regular quaker state, and it has only used a half quart in last 4 years (she only drives it 350 miles a year). i just changed the oil in my jeep that has 217,000 miles on it. this was first oil change on it in 12,000 miles, and it used one quart since last change. yes, i'm doing everything wrong, but it's working just fine for me

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On 10/16/2020 at 7:49 AM, padgett said:

nteresting. Purolator got its start in 1923 but the interweb says "The first use of a full flow oil filter on mass production vehicles occurred in 1946."

Not the first time the "interweb" is wrong.  Pierce-Arrow began full-flow oil filtration on both 8s and 12s in 1933. Presumably >2000 cars in that year counts as mass production.

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1946, what an odd year to pick. They missed Pierce Arrow as Grimy pointed out, but who were they referencing? Chevrolet got it in 1956. Nash still didn't have it in 51. Studebaker got it on the V8 in mid 63. I don't believe any Ford flatheads had it, and those went to 53. I don't recall seeing it on Hudsons. Buick? I don't think they had it in 46. Those external disposable cans on Chryslers were partial flow weren't they? Who adopted full flow filtering in 1946?

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18 hours ago, cheezestaak2000 said:

i'm a little confused about synthetics. back in the 1970's, a rep. from mobil came to the olds shop where i was shop forman and told me only use synthetic oil in a new cae, not in a car with miles on it.i guess he was telling me the truth, since his job was to sell more oil. it would appear that at some point, all of that changed. i'm gonna stay old school on that and used non synthetic oil. i have my reasons, when firestone changed the oil in my wife's 1999 firebird (3.8) it went thru 3 quarts in a month. changed it back to regular quaker state, and it has only used a half quart in last 4 years (she only drives it 350 miles a year). i just changed the oil in my jeep that has 217,000 miles on it. this was first oil change on it in 12,000 miles, and it used one quart since last change. yes, i'm doing everything wrong, but it's working just fine for me

 I don't think that early Mobil One was the same as later. If you remember they used to run TV ads showing it being heated in a frying pan and conventional motor oil burned at a much lower temp. They advertised that it could take higher temps and retain it's viscosity better than conventional oils.

 

But not so in my '72 AMC 304 engine.  I used Quaker State 30W since I bought the car new. Changed the oil every 2000 miles. It gave 65 psi cold startup ( just as AM's were rated it at back then), 55-60 psi highway hot engine, and 20 psi hot idle.  That's measured with a new Stewart Warner top of their line mechanical oil pressure gauge that I installed shortly after buying the car new. 

 

I tried Mobil One 30W when it first came out in about '74. At that time you could only buy it at Mobil gas stations and it was a shocking $5.00 a quart. Cold start 65 psi, 20-25 psi highway hot engine, and at idle the oil light would come on. Which on AMC V-8s back then was rated as coming on when oil pressure dropped below 7 psi.

 

I drained and switched back to Quaker State 30W and the oil pressure readings were back up to what they were before the Mobil One. 

 

So much for that early synthetic being more viscosity stable. 

 

Paul

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Goes with the original Mobil 1 being about 15wt (ATF is 20wt). I used to buy and use Quaker State Deluxe 10W-40 in just about everything (when a $6 case had 24 quarts) and Straight 40wt Quaker State Racing in fun cars, then switched to AMZOIL sometime in the 70's for a bit more power but had to periodically decarbon things.

 

As mentioned when I saw a 2-3 psi drop in idle pressure, I changed to oil and filter. In a DD this worked out to 2000-3000 miles.

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20 hours ago, padgett said:

 

 

Goes with the original Mobil 1 being about 15wt (ATF is 20wt). I used to buy and use Quaker State Deluxe 10W-40 in just about everything (when a $6 case had 24 quarts) and Straight 40wt Quaker State Racing in fun cars, then switched to AMZOIL sometime in the 70's for a bit more power but had to periodically decarbon things.

 

As mentioned when I saw a 2-3 psi drop in idle pressure, I changed to oil and filter. In a DD this worked out to 2000-3000 miles.

---------------------------------------------------

You seem to have missed where I said, "Mobil One 30W".   I stuck with AMC's recommended viscosity.  

 

Paul

Edited by PFitz (see edit history)
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2 hours ago, padgett said:

First Mobil 1s I saw had no weight indication, guess that was before 74.

Well then, I'm not sure where you saw it because according to Mobil their Mobil One for gasoline engine use wasn't available to the USA public before sometime in 74.

 

Paul

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Heck I have a hard time remembering this century. Have always been concerned about oil, for a long time my manta was "Pensylvania grade". Mostly I remember Mobil 1 being too expensive and not having a weight marking but found out later it was about 15wt and designed to help fuel economy, was to light for my extended racing use.

 

mobil1.jpg

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On 10/15/2020 at 11:09 PM, Rusty_OToole said:

Oil pressure is regulated by a spring loaded valve that dumps excess oil back to the crankcase, sometimes by way of the oil filter. What does your owner's manual or shop manual say is normal oil pressure? It seems high to me. Check by putting a mechanical gauge on the engine, also could the oil filter be clogged?

The kind of readings your oil pressure gauge is indicating I think is pretty high.  I don't know what kind of oil was in my freshly overhauled 31 Buick 60 series engine and couldn't ask the previous owner so decided I would go with Shell Rotella 15-w-40 synthetic blend oil.  The oil pressure reading was 35 PSI when I ran the engine with the old oil, is still 35 PSI with the Rotella oil.  I think you have a dirty oil pressure relief valve in play.  The oil pressure relief valve is a spring loaded piston affair and other early Buick inline 8's I've had apart had sticky or stuck valve pistons which is easy to imagine.  The car sits idle for several years with old oil in it and the last thing the pressure relief valve did when the car was shut off for the last time was to settle into it's closed position under the pressure of the spring and with no oil pressure to hold it open.  The oil filter arrangement on these engines WAS NOT a full flow oil filter, that is, the filter was fed off a spur line from the oil pump, in your case, undoubtedly in a canister mounted to the side of the block with a replaceable oil filter cartridge.  In a full flow system oil goes straight from the oil pump discharge to the filter, then to the main oil galleries.  In the Buick system the oil pump feeds the main galleries directly and the filter is on a bypass circuit responsible for filtering the oil and oiling the rocker arms so if it plugs up solid the lifters will get noisy or be starved for oil but it won't have a drastic effect on oil pressure.

 

 

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22 hours ago, padgett said:

Might look here. Have seen hydromechanical erosion in F100 engines and engineers I talked to at GMI said the same thing could happen to a plain (engine) bearing. Of course that was in the '70s, oil today may be different.

i remember when the fine folks at GMI encountered an issue around 1977 or so with the 231 v6 oil light coming on at idle. we had a couple olds omegas come into our shop for that.the tech service bulletin gave us a prt number for a different sending unit. the original was set for around 12 psi, if i remember correctly. they never told us what the new one was.  ahhh the 70's

 

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