Rebuilt Pontiac 301 turbo

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cameradude

Joined
Apr 2, 2016
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Location
Phoenix, Arizona
Hello all,
I want to double check that I have the right take-away from all my lurking here over the past 2 months.

I have a 1981 Pontiac Trans Am with a 301 turbo which was rebuilt just before I bought it 2 months ago. This is the engine that was famous for it's draw through turbo coking oil after engine shut off which led to all kind of problems. I make sure to do a 1 minute idle in the driveway to help cool off the turbo before I shut it off.

The mechanic used high zinc break in oil after the rebuild then put 5w30 dino in it (the manual calls for straight weight 30). I gave it another oil change after 500 miles, again with 5w30 dino.

I live in Phoenix, the car is my daily driver. I have a 25 mile round trip commute for work and the cars sees around a dozen 6 mile RT errand runs each week. The oil pressure seems high to me, after 10 minutes of driving in stop and go traffic it sits at 30 psi at 750 rpm idle. At 2000 rpm it is at 60 psi and above 2500 rpm it levels off at 70 psi. These are all well above the recommended 10 psi per 1000 rpm that I saw listed in the "Motor Oil 101" series on this forum.


I am trying to figure out what oil is best to use from now on, please check my reasoning here:

I have settled on synthetic to help avoid the oil coking issue, my understanding is that the anti-wear agents in newer oils means I shouldn't worry too much about it being low zinc (especially because this is not a performance engine in any sense of the word). Since the oil pressure is high I am thinking that I should switch to a 20 grade, perhaps a 0w20.

Am I on the right track?

Many Thanks,
Todd
 
Todd,
I'd probably go Amsoil ACD for Phoenix in that.

It's "straight" 30 but also a 10W30, with an HTHS of 3.4...in that regard, M1 10W30 HM is similarly built.

Don't change to 0W20 because 101 makes the statement of 10psi per 1,000RPM, that's an old "rule of thumb" for small blocks, as opposed to a statement of fact that pertains to your engine...101 has holes.
 
Originally Posted By: Shannow
Todd,
I'd probably go Amsoil ACD for Phoenix in that.

It's "straight" 30 but also a 10W30, with an HTHS of 3.4...in that regard, M1 10W30 HM is similarly built.

Don't change to 0W20 because 101 makes the statement of 10psi per 1,000RPM, that's an old "rule of thumb" for small blocks, as opposed to a statement of fact that pertains to your engine...101 has holes.


LOL!

Don't ever listen to this person.


Keep using a quality synthetic 5w30.
 
Originally Posted By: cameradude
Since the oil pressure is high I am thinking that I should switch to a 20 grade, perhaps a 0w20.


Yeah you go ahead and do that. Meanwhile, start pricing crate engines.
 
Oil 101 is mostly opinion and little if any fact. Don't consider yourself educated by oil 101.
 
I'd go with a 10w-30 as well. A lot of stout ones out there. I doubt there's a bad one out there, but if you want a lighter 30w, I'd recommend pretty much any of the Pennzoil 10w-30s. They all seem to be in the 10-10.5 cst at 100c.
 
Id go with a nice dose of 15w40.
3000MI oci,
Decent middle ground filter, something that's decent flow, decent filtration, but nothing fancy like an STP Extended Life filter, id go with something such as a Fram Ultra, not too bad, not too good, but doesn't have those gosh darn sliver things!

Trolling.gif
 
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In all reality though, Id go with a 15w40, you're in Phoenix.
I'd keep a conservative 3000mi OCI
and I'd slap a regular Wix, Mann, OCOD, Delco, STP, Microguardedsupertechedpromotivated filter on it. nothing too fancy
 
Originally Posted By: KingCake
Originally Posted By: Shannow
Todd,
I'd probably go Amsoil ACD for Phoenix in that.

It's "straight" 30 but also a 10W30, with an HTHS of 3.4...in that regard, M1 10W30 HM is similarly built.

Don't change to 0W20 because 101 makes the statement of 10psi per 1,000RPM, that's an old "rule of thumb" for small blocks, as opposed to a statement of fact that pertains to your engine...101 has holes.


LOL!

Don't ever listen to this person.


Keep using a quality synthetic 5w30.


I would take Shannow's advice.
 
nope cool off is 5 minute warm up is 100 farenheit. i would put straight oil in it ,it isnt to [censored] you off that they have spec .if you really want to put something else? put same oil i put in my car its 38.99 at ta travel center.the adventage straight oil has for oyu ? very inexpensive and easy to get, as for 101 article ? dont sweat it , he isnt wrong in the article.
 
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No, you're not on the right track.

https://en.wikipedia.org/wiki/Pontiac_301_Turbo

The Wiki page for YOUR engine states:

The 301 Turbo was unique in that it had a stronger block with thicker cylinder walls than the '77-'81 301 naturally aspirated unit, it also had newly developed internal components, such as for example lower compression forged pistons, (lower compression due to the forced induction pressure of the turbo system) a relatively mild camshaft, a high pressure oil pump (60 psi) to ensure adequate oil to the oil-cooled Garrett TBO-305 Turbocharger, a rolled fillet crankshaft with 2 instead of 5 counterbalances, a fully baffled oil pan, and a high pressure fuel pump (10 psi)...

Sounds to me as if your "high" oil pressure is normal for this engine; being DESIGNED that way to assure adequate oil to the turbocharger.

Additionally, the factory engineers designed tolerance for wear into the oil pressure system; for example, I drive a 2003 Buick Lesabre with the bulletproof 3800 V-6 in it. MY GM-written factory service manual calls for 45 psi oil pressure at 2500 rpm. My car has 70K very well maintained miles on it and I have 62-65 psi oil pressure from a cold start, about 55 psi at a warm idle (~800-1000 rpm), cruising at 70 mph it will run 60-62 psi oil pressure all day long, and if I try to run my accelerator foot thru the floorboard, it will peak oil pressure at about 70 running 80-100 mph.

I have V-rated tires and an aftermarket PCM with the rev limiter removed; (among other modifications), and yes, the car will run 100 mph+ for extended periods...Obviously, I don't do this in town or where visibility is less than about 3 miles...Not trying to kill anyone or go to jail.

My point is, I used to have an older Buick, same engine, 200K+ miles, it idled with about 17 psi oil pressure hot and peaked about 55 psi oil pressure at speed...The engine was obviously worn more than my current driver. And all the above comments apply with the same viscosity oil in both engines, and when the engine is fully warm, it shouldn't matter if you're in Alaska or Florida, the engine and oil temperature will be the same.

Bottom line, I believe what you have stated as oil pressure is NORMAL for your engine. I would agree with the switch to synthetic, because it will better withstand the higher oil temps from your turbo, but stick with a 5W 30 or 10W 30. You do not need to lower viscosity in an attempt to lower oil pressure. Let the engine function as designed.

That's my two cents. Do whatever lets you sleep at night.
 
Originally Posted By: KingCake
Originally Posted By: Shannow
Todd,
I'd probably go Amsoil ACD for Phoenix in that.

It's "straight" 30 but also a 10W30, with an HTHS of 3.4...in that regard, M1 10W30 HM is similarly built.

Don't change to 0W20 because 101 makes the statement of 10psi per 1,000RPM, that's an old "rule of thumb" for small blocks, as opposed to a statement of fact that pertains to your engine...101 has holes.


LOL!

Don't ever listen to this person.


How about you provide some supporting evidence as to why the O/P shouldn't, instead of spouting off?
 
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The Eric,
the problem is that I called King Cake out a couple of times on his erroneous advice that a 5W30 will "always" "flow more" than a 10W30 at any and all temperatures.

Each time, he's not answered, and then gone on to repeat in other threads...This way it's easier.

On the other hand, I'm quite happy to justify my ACD recommendation.

It's a synthetic monograde that is good enough to be a 10W30 without any VM additives...i.e. it's a solid basestock. Being a monograde, it's not relying on the presence of polymeric VMs, which can under extreme conditions lead to deposits and varnish (and loss of operational viscosity).

WRT the OP's description, the turbo is non water cooled, and the brand has a history of deposit formation...turbo is mounted high, inlet and oil drains on top of the bearing block, the few ounces of oil that are in it on shutdown are there until next time it's started...

...in particular to the OP's post point, the 0W20 would have WAY higher volatility (NOACK), Flash point, and Fire Point...and lower allowable TEOST (deposit formation) than the allowable for a 0W20...on that line, the only analyses I've seen are a more traditional ad-pack, without moly.

WRT the 5W30, and the absolute lack of need of a 5W in Phoenix, much the same argument applies, but lessened some.

Draw through carbed turbo will have some pretty rudimentary enrichment under boost, which is likely to be overly rich at other points and lead to fuel dilution...possibly why the OEM recommended straight 30 with it's higher HTHS than the multigrade 30s at the time, but certainly why I'm recommending what I am.

I still stand by a VM free, synthetic, old school additive pack, low volatility, high flash/fire point SAE30/10W30 in this application.

And 101 is seriously flawed, if that's his point as well.
 
Another vote here for a 30 weight, but I'm out on a limb and going to say the 15w30 from Delo gets my pick here. For all practical purposes, a straight weight with multigrade qualities, it is marketed for the delivery industry where there are multiple starts and stops on a route and the turbo heat soaks each time. No 20 weights in this motor though...
 
I owned one of these cars back in the day with its Buick V-6 sized turbo charger and the only thing that has survived to this day is the owner's manual (I just re-read it this morning). I would not run a xW-20 in that engine--even Pontiac stated not to use it in higher ambient temperatures or sustained high speed driving. I would not worry about the oil pressure either, as others have said, the oil pressure was designed to be that high due to the requirements of the engine and turbo.

You are correct that coking is a problem and even though I installed an "after shutdown" oiling system on mine, it still coked up--just the consequences of the "weak" oil from that era and a bad design from GM. I would only run a synthetic in the engine, I would allow it to idle down before shutting it off, and I would be looking at a synthetic HDEO (Delo 400 LE, Rotella T6, or Delvac 1 ESP), a Euro 0W-40, or something on the lines of M1 15W-50 to use in it.

Pontiac could really have built a Screaming Chicken had they used a larger turbo. I replaced mine with a 455/Doug Nash 5 speed/12 Bolt rearend when it coked up. Ah...those were the days. Good luck!
 
Originally Posted By: KingCake
Originally Posted By: Shannow
Todd,
I'd probably go Amsoil ACD for Phoenix in that.

It's "straight" 30 but also a 10W30, with an HTHS of 3.4...in that regard, M1 10W30 HM is similarly built.

Don't change to 0W20 because 101 makes the statement of 10psi per 1,000RPM, that's an old "rule of thumb" for small blocks, as opposed to a statement of fact that pertains to your engine...101 has holes.


LOL!

Don't ever listen to this person.


Keep using a quality synthetic 5w30.


LOL! LOL!

Don't ever listen to KingCake.
 
Last edited:
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