Diesel motor oil in a gas engine

[cyoung1253]

What's the difference between motor oils labeled for use in "hard working diesel engines" and those labeled for gas engines. If the oil for the diesels has better lubricating properties and/or a better detergent package wouldn't it be better for a lil ol 5.3 gas engine? I was looking at the Mobil 1 Truck and SUV 5w40 for diesels and the Mobil 1 Truck and SUV 5w30 for gas engines and said to myself Hmmmmmm.

Any harm in running the 5w40 in a 5.3? I know GM reccomends 5w30 but is the lighter weight oil for fuel mileage reasons only? Wouldn't the slightly thicker 5w40 lubricate better at operating temp while still having the same flow qualites at cold start-up?

 

Thanks

[redvett]

Running a higher viscosity oil than reccomended isnt goood with the closer clearances in newer engines.

[C & A s Dad]

Ditto on the viscosity but you also should not run D oils in your gas burner. The oil for a D is formulated differently to handle a much nastier running engine and I can tell you that I don't think you will find a technician or oil co recommend D oil for a G burner.

 

Use Mobil 1 of Amsoil 5W 30. You can't get any better than that.

[5.3isnota327]

Diesel oil actually works better in an old style engine with a flat tappet camshaft. There is more zinc and I think phosphorus in them, and flat tappet cams love it. The bearing clearances between the old SB and the LS1 style engine are pretty close to the same. Actually a little thicker oil might help if you have some piston slap. The thicker oil will cut down on gas mileage a bit though.

[OnyxMAX]

as long as it still meets or exceeds the oil specs for you engine it should be ok although i would go with 5w30 d spec if i went that rout.

 

now weither it's beter or not thats like asking what brand to buy or dino v. syn.