streetsmoker

I'm just curious to see if anyone here is currently using the 10w30 multi-blends such as Rotella t5, Delo XLE, or Delvac Super? If so, at what point do these begin thermal breakdown, add I know the full synthetics handle higher oil temps better. Thinking of switching to this for the added increase in mileage it claims to provide.

Oh, and this is for a different truck than the one in my signature. As its been a while since I updated.........LOL!!!!

MikeyB

Living in the deep south I would stick with 5w-40 or 15w-40 in the Cummins. 10w-30 would be fine in the winter months in the frigid north.

Harvie

You do not need to spend the extra money, straight Rotella 15-40 works just fine and at 12.97 a gal at wallymart it can not get any better then that.

Busboy

Actually in the "frigid North" paper version of the owners manual it states that engine damage may occur if 5W 40 is not used in the winter months. I just run it year round towing heavy.

ofelas

I believe a 30w was Cummins fill until 89 or so.

Modified to a 40w soon after as most mineral multigrade 40w oils would shear down to a 30w anyway (a multigrade 30W would sometimes shear down to a 20W).

A semi synthetic or full synthetic 30W would do just fine, as flow is what protects bearings more than pressure does.

Not to mention a 30W is likely better for turbo bearings & piston cooling nozzles.

rjm022

My neighbor has been a heavy equipment mechanic for many many years. He also has an 04 Cummins. He uses semi synthetic 10w-30 oil since he bought the truck new. Truck has 130,000 miles on it. Says most the heavy machinery he works on also uses 30 weight oils