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?
Why on Earth is this working so well?