high mileage oil for an older turbo car

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firebird72

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hi, first post here but been a reader for many years...

i have an older 1981 pontiac turbo v8 engine & was wondering what the opinions on using a high mileage oil in it are? my main concern is the seals in the turbo, would the HM oil have any negative effect on them? like swell or harden them?

the car doesnt technically have high miles, its original 29,000 miles but the car is 35 years old & has a very minor rear main seal leak, just a drop or 2 when parked so its not bad at all but i thought using a HM oil might help seal it up & HM oil is usually a "better" oil as far as thickness & zddp levels which would be a benefit to this older car with a flat tappet cam. i am considering the synthetic or blend HM versions to benefit the turbo, but not sure if i trust the leak with synthetics.
 
The car will be fine with some Valvoline Maxlife syn-blend 5w30 or some Pennzoil High Mileage 5w30 etc. The HM oils will help condition the seals and you don't have to keep using HM oils. Maybe even alternate btwn HM and conventional/syn-blend oils. Just be patient with the results and don't change it out too soon.
 
An HM oil will swell up the turbo oil seals, although not to the same degree as a major brand stop leak additive.
I would never use an HM oil in a turbo charged engine unless it had oil leaks that were beyond economic repair. It can cause the oil seals to fail faster, due to increased pressure on what is often a pitted shaft.

If your oil consumption is high, make sure the CCV is working and not sludged up or suffering from a stuck valve. Then try using an idle use only flush additive just before changing the oil and filter to a certified OEM spec filter and a major brand oil that is one group higher. So if you have been using an Xw30, move up to an Xw40. If it's real bad, I would try Mobil 1 10w60 EL (It's an HM oil) and half a can of LM Ceratec.

The oil seals will last longer if you use Ceratec to fill in some of the voids in the shafts that the oil seals push against.
 
Last edited:
Originally Posted By: rooflessVW
Mobil 1 5W-30 High Mileage would be my choice.
+1

My grandfather's 96 Jeep Cherokee has always leaked a little. I replaced the oil pan gasket and RMS and it still dripped with MaxLife and Chevron Supreme HM. Put Mobil 1 HM 10w30 earlier this year and crawled under it the other day, dry as a bone. It's never been dry under there before.
 
Originally Posted By: UltrafanUK
and half a can of LM Ceratec.



This is your answer to EVERYONE'S problems! Are you paid on commission or what?
 
Come on Aquarius, 20W-50. Castrol HM if I had to guess.
wink.gif

Seriously, a 20W-50 or mono grade 30 would be my pick.
 
Originally Posted By: Red91
Come on Aquarius, 20W-50. Castrol HM if I had to guess.
wink.gif

Seriously, a 20W-50 or mono grade 30 would be my pick.


Haha you read my mind! (As I look down at my two jugs of Castrol 20W50 sitting next to my desk)
wink.gif
grin.gif
 
thanks for the suggestions. im not really asking which brand or weight oil to use, more concerned about the turbo, ultrafanUK mentioned the concerns, a turbo has an oil seal around a shaft that spins very high rpms, im not sure if a HM oil will be good for that if it swells the seal.

the engine has great compression & doesnt consume any oil, also all other gaskets are new & the heads were rebuilt a few years ago with new valve seals, so the high mileage isnt needed for other gaskets & seals, its just the rear main seal that drips a bit.

if there is any question about the HM oil & the turbo i will just use a quality conveentional oil or maybe a blend & deal with the minor seal leak as i have for years.
 
knowing that most of todays "synthetics" are severly hydrocracked mineral oils technically group III + semi-syns have NO laws governing the amount of "synthetic" usually group III oil used in the blend i would opt for a $5.xx synthetic as it will handle the turbo heat better. if you are in a warmer area a 10-30 may do better since it uses less viscosity improvers. i put a true PAO-Ester synthetic in a 122,000 mile 64 olds cutlass 20 years ago , yes it dripped a little but ran well until 250,000 when i sold it!!!
 
HM oils have seal conditioners. They cannot swell a seal beyond its original dimension. Mostly they soften them. And after that many years, they are getting "firm" to say the least...

I'd try it. I've run all sorts of oils and additives in turbo motors. The turbos themselves are pretty forgiving of everything but not enough oil, or oil coking which will not happen unless it's plumed wrong, or has a restricted return line ...

I run Maxlife in newer flat tappet motors for the add pak. It's pretty good oil for a money
smile.gif
 
Last edited:
Originally Posted By: firebird72
thanks for the suggestions. im not really asking which brand or weight oil to use, more concerned about the turbo, ultrafanUK mentioned the concerns, a turbo has an oil seal around a shaft that spins very high rpms, im not sure if a HM oil will be good for that if it swells the seal.

the engine has great compression & doesnt consume any oil, also all other gaskets are new & the heads were rebuilt a few years ago with new valve seals, so the high mileage isnt needed for other gaskets & seals, its just the rear main seal that drips a bit.

if there is any question about the HM oil & the turbo i will just use a quality conveentional oil or maybe a blend & deal with the minor seal leak as i have for years.


This is my opinion. There are high ester content PCMO's such as Redline and Motul. There is no "caution" about using high ester content oils for turbo seals. HM oils are ISLAC GF-5/API SN certified and seal compatibility is tested for the certification.
 
That is really low mileage,almost scary low. Try Quaker State Defy and drive it normally. If it doesnt give you any trouble then go M1 HM or Castrol Edge HM. The M1 I believe is SL of SM so more Zinc and such,but the Castrol Edge or even Valvoline Maxlife Syn is probably better with seals. Being 81', many seals might be cork gasket.Another alternative is run Pennzoil/Quaker State Synblend with Liquimoly Motor Oil Saver LM2020. It will turn oil into HM and increase viscosity to help Turbo.
 
Originally Posted By: zrxkawboy
Originally Posted By: UltrafanUK
and half a can of LM Ceratec.



This is your answer to EVERYONE'S problems! Are you paid on commission or what?


No cos if you look at my sock puppet name it's UltraFanUK, not LiquiMolyFan. So I'm a Shell GTL technology oil fan, although that is partly because LM Synthoil is too expensive, even in Germany.
If you do have an out of warranty worn engine or an engine subject to severe service use, Ceratec is the dogs two small round things, although in many applications you only need half a 300 ml can.

In some cases where oil leaks or high oil consumption is an issue, Ceratec use can reduce the drip or consumption rates. This is when the shafts passing through the oil seals are old enough to have suffered from corrosion causing pitting that is one cause of worn oil seals in the first place. Using a normal Moly (Mo) additive can also have a similar effect sometimes.
 
Last edited:
Originally Posted By: BrocLuno
HM oils have seal conditioners. They cannot swell a seal beyond its original dimension. Mostly they soften them. And after that many years, they are getting "firm" to say the least...

I'd try it. I've run all sorts of oils and additives in turbo motors. The turbos themselves are pretty forgiving of everything but not enough oil, or oil coking which will not happen unless it's plumed wrong, or has a restricted return line ...

I run Maxlife in newer flat tappet motors for the add pak. It's pretty good oil for a money
smile.gif



I would trust BrocLuno on this. He has run red bottle (semi-synthetic) Valvoline MaxLife HM in all manner of vehicles of all ages. If he's not concerned, then neither am I.

Also I believe that regular oils also contain seal conditioners, just HM oils contain a little more. These HM oils are well tested by the factory, and well used by many here, and I've never heard of any problems.
 
The turbo seals in a 1981 turbocharger will be a mechanical design, made of metal, you're not going to swell them with oil. Turbo seals are not like crank or cam seals.
 
Originally Posted By: supercity
The turbo seals in a 1981 turbocharger will be a mechanical design, made of metal, you're not going to swell them with oil. Turbo seals are not like crank or cam seals.


Good to know SuperCity.
 
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