2stroke oil in your gas
Diesel fluel has also gone to the shitts the past years all this low emissions has taken out vital sulfer and minerals out of the diesel fuel which alot of old diesel engines need. I have been compensating for this by running wally marts 2 stroke oil and can actually tell a milage diff. and seems to run quieter. I think all diesel should run if for sure but i have no input on gas engines.