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Discussion Starter #1
Hey guys, simple but crucial question, what is the right oil to use in a Pontiac 400? 10W 30 , 10w 40? How many quarts as well ?It has a roller cam in it as well. Its a simple question but important.
 

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is the 10w 30 to light for these old motors?
No, 10W30 is not too light...unless that engine was specifically built for racing us and has unique oiling requirements, or if it needs higher viscosity lubricant due to component wear.


The OEM oil recommendations (from the Factory Service Manuals) were as follows:

For operation in temperatures from -30F to +20F: 5W, 5W-20 or 5W-30
For operation in temperatures from 0F to 60F: 10W, 5W-30, 10W-30, 10W-40
For operation in temperatures from 20F to 100F or above: 20W, 10W-30, 10W-40, 20W-40



I also use the Brad Penn 10W-30 that Matthew recommended. I believe the higher zinc content is better suited to the flat tappet cams/lifters. If I had a roller cam & lifters, I would probably use a "normal" 10W-30 brand.

Double check the capacity; I think your 400 should take 6 quarts with a filter change.
 

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A lot depends on how the engine is built. Are bearing clearances a little on the tight side? a little on the loose side? What kind of camshaft are you running? (flat tappet or roller). What's the climate like where the car's going to be most of the time? How are you going to drive it? What's the rest of your oiling system like? (pump, pan capacity, etc) --- and how well is it sealed? ( a leaky rear main can make running synthetic oil very expensive )


In my car, I'm running Rotella T 15w-40. It's a "performance" engine build (bearings just a tiny tiny bit on the "loose" side), it's running a solid roller cam, I live in Texas, I drive it mostly on the street and also race it some, I'm running the Snelling M54DS pump with this backing plate this pickup, and this oil pan, and (sorry to say) my rear main seal leaks a little.

My factory oil pressure gauge shows 75 psi on a cold engine, about 65 psi at cruise with a warm engine, and about 20 psi at idle with a warm engine.

Bear
 

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Discussion Starter #8
Im not really sure on the specs on the motor because I did not do the rebuild. I do know it has a mild to heavy cam in it. I also live in New Jersey. Everything else is stock such as oil pan and oil pumps etc. ?
 

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Looks like you have a roller cam, which means you have plenty of good options, and do not have to worry about the extra zinc. I have a flat tappet cam, and my engine guy recommended 15/40 with a zinc additive. With this combo, I managed to lose two lobes off a hyd cam within the first 1,000 miles.

When watching how long it took for 15/40 oil to get forced up through the pushrods and rockers on cold start, I stopped using it. I also read on Bobs the oil guy.com that the high detergent found in 15/40 diesel oil would actually offset the properties found in the zinc additives.

I have a relative that works for Amsoil, so he got a me a good deal on a case of zrod 10/30 high zinc oil. Short of a cam issue like I originally had, I do not put nearly enough miles on the car to tell any difference on oil one way or the other. I will say however, my solid lifter engine feels smooth with the zrod oil, but maybe I am just eating up the marketing hype :)


Being that you live in a cooler climate like I do, and likely start the car on cool fall nights, I would run a name brand 10/30 or 10/40 oil. A synthetic blend might be a good option as well, and maybe provide a little better start up protection.
 

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Factory fill for a '67 400 was 10w 30. My stock '67 GTO 400 engine holds SEVEN quarts with filter. My '65 389 holds only 6. Later 400's held less. Have been using 15/40 Rotella in the '67 for about 10 years and 20,000 miles with no issues with the 068 cam I installed 25 years ago whatsoever. I am in the lighter-viscosity-is-better school of thought, though, and would think Brad Penn 10w30 with the ZDDP would be a great choice.
 

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I like what BearGFR says. I run similar oil...Delo 400 30WT in the stock flat tappet '69 400. When I went through the engine I even broke sacrilege and used the original cam with new lifters and Crane energizer true roller rockers. High pressure pump, stock sump and pan. It runs hot low idle in gear(auto) about 24-25 psi. Touch the throttle and it jumps to 65+ and runs there. In my '64 ('68 400) I use Delo 400 15W-40. It has a roller cam, 11 qt capacity road race oil pan, High pressure oil pump,Crane Energizer true roller rockers, Aluminum heads, etc. It runs 29 psi hot low idle(900, big cam) and constant 75+. I also run in all my engines full circle oiling main bearings and .025 oil restrictors in the lifter galleries. Needless to say since I can build my own stuff I very seldom bring these cars home without a thorough thrashing first. Also I do not use stock cast rods, but forged ones (the old 'rubber rod').
 
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