Your car, boat or truck may have a problem with oil leaking into the combustion chamber. You can diagnose this yourself by checking the color of the exhaust from your vehicle. Fuel does not leak back into the engine oil, but there are a few reasons why oil could leak into the engine.
Your diesel engine should produce clean, or almost clean-looking exhaust without a hint of smoke or color to it. If there is no smoke coming out of the exhaust, the oil probably isn't leaking into the combustion chamber.
If there is a blue hue to the smoke coming out of the exhaust, you may have overfilled your engine with oil, which causes a pressure buildup and leakage into the combustion chamber. Letting your vehicle to run at idle for too long, without allowing the engine to increase RPMs, can also cause oil to leak into your diesel engine.
Drain some of the oil in the engine to determine if that is the cause. Rev the engine and drive the vehicle at increased speeds for 10-15 minutes. Recheck the color of the exhaust. If the problem persists, there may be an issue with the gaskets in your engine and your vehicle might need professional repair.
