Petrol or Diesel oil- any difference?

[Chazchuzzlewitt]

I have some spare oil that's marked for diesel engines, and I wandered if I can use it in my new petrol car? Is there actually any difference in the oils or is it all just marketing?

 

[LNM]

They've got different weights / viscocities so unless it fits inside the guidelines in 't manual, I'd not use it.

Be a shame to cabbage an engine by putting the wrong oil in it.

 

[Sprint'n'Go]

Stop right there

Under no circumstances should you put a diesel oil into a car with a catalytic converter. The extra additives used in diesel oils will wreak havoc with the cat. It is precisely for this reason that oil manufacturers are now selling euro4 specific diesel oils as the latest diesel engines also have cats. You could put petrol engine oil into a diesel at a pinch but service intervals would have to be slashed as the detergency additives would be insufficient to deal with the soot that gets into diesel engine oil.