Motor oil in Cummins AUTO transmission.

[JT1]

My buddy has been running Mobil 1 5w30 in his Dodge Cummins powered pickup since its last transmission rebuild over 100k miles ago, and it works great. He does it because the rebuilder suggested it. I've driven this vehicle and the transmission works perfectly normal even on a cold morning, zero slipping, banging, etc. He only drives this vehicle if he has something to tow, so it's basically had over 100k towing miles on it with no issues.

Why on Earth is this working so well?

 

[Red91]

Are you saying he's running the oil in the transmission?

 

[Highline9]

I run tractor hyd. transmission fluid in some of my automatics. Good for him, high hp turbo guys run mobile one in there 3 speed and powerglide automatics too. Glad to see im not the only odd ball.

 

[DSparks]

Yep ..drag race guys been doin it for years...I was like [censored] when I first saw it too ....seems to work good.

 

[Red91]

Never heard of it. Wonder if something of the sort would work in an NV3500 manual 5 speed?

 

[caravanmike]

some of the allison ht 700 series auto's did take 10w-30 as an option.

 

[JT1]

Originally Posted By: Red91
Are you saying he's running the oil in the transmission?


Yep.

 

[Highline9]

what trans is it or year is it?