Str8-8-Dave Posted July 22, 2019 Share Posted July 22, 2019 So my 1931 Buick 8-66S is now a running car. Before I ever saw it someone overhauled the engine, restored the drive line and chassis. I don't have a clue what was done inside the engine, I've only had the valve cover off where I discovered some threaded rod was used to attach the cover, I replaced with studs, and it has aluminum valve spring retainers. Outside I campaigned the fuel, ignition, exhaust systems and went back to stock oil filter branch fitting and installed a filter that looks like original (kind of) and hides a spin on cartridge. Inside the valve cover and as far down the oil filler as I can see it is clean as a whistle internally and the oil that was in it is clean and clear like new. There are no coolant leaks. It still runs a functional oil temp regulator. It does 30PSI oil pressure hot at idle and 35 as soon as you increase the engine RPM. Now I want to use an appropriate oil that is readily available. I'm considering Shell 15-w-40 Rotella T-5 synthetic blend diesel oil which I think might a pretty good all round oil and has some ZDDP in it. Does this sound like a good choice? Link to comment Share on other sites More sharing options...
Spinneyhill Posted July 22, 2019 Share Posted July 22, 2019 Yes! CJ-4 has slightly less ZDDP than CI-4 oil but still a good choice. Full synthetic will be better at reducing wear. Link to comment Share on other sites More sharing options...
raydurr Posted July 22, 2019 Share Posted July 22, 2019 Does the 1931 Buick engine have roller lifters or flat tappet lifters? My 1929 Buick has roller lifters or "followers". The rollerized cams have significantly less friction. Even though I run high ZDDP oil , it may not be necessary. Link to comment Share on other sites More sharing options...
stvaughn Posted July 22, 2019 Share Posted July 22, 2019 This stuff seems to work good for me. Holds 30 psi oil pressure on long drives in 90+ F temperatures. Link to comment Share on other sites More sharing options...
Str8-8-Dave Posted July 23, 2019 Author Share Posted July 23, 2019 Thanks to all for the advice. Spinneyhill- for the amount of running the car will get I'm thinking I'll save a few bucks compared to full synthetic and change it a little more often. For now it gets run for 20-30 minutes and doesn't go anywhere because it is still on jack stands and has no seat in it. I have ZDDP additive in 2 0z bottles I can add as well. Raydurr- 31's and probably many other model years before and after had roller tappets. Link to comment Share on other sites More sharing options...
raydurr Posted July 23, 2019 Share Posted July 23, 2019 Dave I thought the Buicks had rollers till 34-36. I run ZDDP oil , but I wouldn't lose much sleep over the amount of zinc due to having roller cams. Link to comment Share on other sites More sharing options...
Spinneyhill Posted July 23, 2019 Share Posted July 23, 2019 If you have roller tappets, zinc is much, much less "necessary". Changing the oil more often with mineral oil doesn't do the same as running synthetic. It is the cold start that is the problem. Wear tests show that any synthetic oil is better than all mineral oils at minimising wear. And the lower the number before the W, the lower the apparent viscosity at low temperatures (I don't mean -10oC, I mean 10-15oC) and the earlier full oiling occurs on a cold start. 1 Link to comment Share on other sites More sharing options...
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