Schaeffer 0700CK4-006 SynShield 15W-40 Diesel Engine Oil - 1 Gallon Bottle (6 Pack) | High Performance Synthetic Blend for Heavy Duty Trucks, Construction Equipment & Fleet Vehicles | Extreme Temperature Protection & Engine Longevity

My dad started using this in his 7.3 Ford diesel after talking to some off-road guys. They said at the angles that they drive on their engine seem to run a lot better and cooler do they the oil sticking to the walls of the block better. Since my dad used it I started using it in my 5.4 Ford and it quieted the motor down a lot. I will definitely use again and continue to use it.