What Weight Engine oil do You Run?

What weight engine oil do you run in your older dozers? I've read quite a few articles and it looks like the recommendation is for 15W40 in place or straight 30 weight for most conditions even if only using above 30 deg. The thinking is today's oil viscosity additives are much better than they were a few years ago and it does not reduce the protection offered.

What do you think?

I have switched to 15W-40 in both the D2 and the D7, both main and pony. It works fine. In my area temp runs from 90F high in summer to 10F in winter. It occasionally gets hotter and colder but we seldom run either Cat at those times. Cold weather starting is easier, especially for the crankup on the pony motors.

I use Chevron Delo 400. It's good, Mobile Delvac is better but harder to get here. There's a lot of other good oils out there. Just be sure it's suitable for diesel engines.

Jack

When I was working yet a good percentage of the truckers liked the Shell Rotella 15/40 & boy when I took an engine apart that had it used in it they were as clean as if it was a new engine.

I hadn't had the opportunity to operate a cat for 30+ years until last summer, when a friend of mine put me to work on his 46A. He is one very fussy guy when it comes to maintenance and changes the oil on all his engines at 100 hrs. He uses 15-40 year round, but doesn't do much work in the winter. He said the engine on the 46A I was operating has a bit over 21,000 hrs on it, and has yet to have the heads off. It has only seen 15-40.