If one of the symptoms of faulty injector o-rings is oil getting into the fuel, how do you detect that, assuming the oil goes into the fuel return line and back to the tank? Or does it get injected into the cylinder and burned producing excessive smoke? Are there other symptoms to look for?

 

Your fuel filter will be black from the oil.

 

So that would take awhile to accumulate, assuming it goes back to the tank first, right?