It think putting ATF in a gas car is a quick way to kill the cat.

The oils are compatible. It is that the diesel specific oil suspends dirt particles better and also has, as I understand it, better detergents.

I am about to change the injectors on the 93 190e. I am wondering if your car, being a 1989 300E, might not also be a candidate? Every so often before an oil change, I will run a double-dose of Techron Fuel Injector cleaner in less than a full tank. I will drive the car fairly hard (once warmed up) and it does seem to help. But if your injectors are leaking and stubling at startup is a sign, no cleaner will cure the problem.

Haasman

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'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)