If this is an original motor, not rebuilt, better to run the straight weight 30 non detergent - that is what it ran with previously and any detergent oil could do more harm than good. If it has been rebuilt, as are mine, I use 20-50 detergent oil and I change it fairly frequently since I do not run an oil filter.
Pete, that's interesting. Those syn oils were designed for high tolerance engines. How long have you been using it? And are you using any between oil changes?
Its been in about a year and a half, About 3 thousand miles so far,I plan on changing it once a year(3-5 thousand).Does not leak or use any oil.I also use it in my 1937 Chevy truck(305 SBC)Change it once a year(5-8 thousand miles).Both daily drivers use the same oil(change every 10,000 miles)Been in since new,one has 73,000 and one has 61,000 miles.I also use it in my sons commercial lawn mower(Kawasaki 19 HP) Power washer,generator,push mower,snowblower.I buy it in the 5 quart jugs.I add zink to the flathead and SBC.Pete
540 RAT makes some very important points, for one, too much ZDDP is also harmful. But it is interesting while he claims over and over he is independent - when "Oil Extreme Concentrate" improves the performance of an oil the flowery descriptors on just how wonderful the additive is are abundant, but when the additive does little or even degrades (and some oils get worse according to his tests) he says little to nothing. Hmmmmm . . . The good news is flatheads in most forms do not have a lot of valve spring pressure so ZDDP levels are not super critical. Shell Rotella and Delo 400 are both good oils to use (I use 15W-40 Delo with no additives in my supercharged 8BA). But even with the low spring pressures I'd be nervous using any of the oils designed for modern gasoline engines.
The Jalopy Journal
