Q: I have been using 20W40 engine oil out of ignorant for two years now on my Passat cc But I found out that the right oil is 5W30 or

Hi Justin. Thanks for taking time to contact us today. First off - don’t worry, you’re not the first person to make this common error. Although higher viscosity engine oil is not always the best way to protect an engine, it’s not too harmful either. In most cases, the biggest symptom that will occur is that oil pressure will be higher than normal, which would have triggered the check engine or oil pressure light on your dash if a problem existed. If this has not happened, then it is likely that making the change to the recommended 5w30 should not cause additional problems. The only thing that would cause smoke is if piston rings or cylinder head valve guides were damaged slightly due to the higher viscosity oil - but I would not worry too much about that. Just make sure to change your oil and oil filter at the same time, and you should be fine.