The other day, after driving my M37 for approximately six I noticed that the oil lines to the stock remove oil filter were still cold. That tells me that in the six miles that I usually drive to town and back the filter isn't warming up enough to stop by-passing.
With this in mind, I'm considering changing to straight 30W non-detergent oil.
I'm told the big advantage to modern detergent oil is that it keeps dirt and crud in suspension so a modern, high efficiency oil filter can remove it. The way I see it, in an M37 there are two problems. First, the stock canister oil filter is far from being high efficiency. At 20 micron you could throw a cat through it. Second, the stock filter appears to be by-passing most of the time during sold weather season.
Therefore .... "PLESE CORRECT ME IF I'M WRONG" ... The "Modern" detergent oil is keeping the dirt in suspension where it is not being filtered/cleaned and therefore is constantly curculating the dirt and crud in suspension through the engine instead of allowing it to drop out and into the bottom of the pan --- as non-detergent oil would. I think I'd rather have the dirt in the bottom of the pan than constantly curculating through the bearings.
Under this scenario, it seems more logical to run non-detergent oil and change it often.
We are installing the new pistons, rings and rod Thursday. I'm also installing an oil pan heater so the straight 30W won't cause cold start problems. I've come to the conclusion that it's "always" best to start 'em warm --- plug 'em in.
What do you think about running non-detergent oil???