This is a question on a 95 E-350 with a 7.3 powerstroke. When I got it it was smoking and banging, but I replaced injector seals and then it was great. Then I had the oil changed at Ford and after about a hundred miles it would not run any more. It was 10 quarts low. I thought maybe they forgot to fill it up, but then after another hundred miles same thing. This does not smoke and no visible signs of major oil leaks. Any ideas anyone???!!! :confused:

Injector seals...again. The oil is going into the fuel. Not exactly common, but it does happen.

Yes, warm it up and the exhuast color will be discolored, since the oil is getting into the fuel and combusting.

The most reliable way to tell if you have oil in the fuel is to remove the fuel filter cover and check the fuel color. If it is brownish/blackish you definately have oil in the fuel.