10-30 diesel vs 15-40

aceltx · Feb 28, 2015

I Only had my 7.3 about 2 months when i got it I changed all the fluids and filters in it. got everything from ford, so much fluids purchased at 1 time i didnt pay attention to what he gave me when i got around to the oil, i noticed ford dealer gave me 10-30 diesel, i called and said hey whats up why didnt you give me 15-40, they said thats all they use now if u bring a truck in there for oil change thats what they put in.
So i used it, engine runs fine except for crappy fuel mileage (probly due to big tires and leveling kit) what do you gusy use and what you think about 10-30 diesel?

08Monster · Feb 28, 2015

Thats what we use at CAT too.

BS Hauler · Mar 1, 2015

That's what I run in my 7.3 and 6.0

Carolina444 · Mar 1, 2015

Any benefit from 10w30

08Monster · Mar 1, 2015

Easier cold starts, and starts sending oil through the filter faster. Cold 15-40 will never flow through a filter, so it just bypasses it. Watch a cold oil flow test on YouTube or something and you'll see what I'm talking about. And why we switched