ok my buddy argues with me he Has to put non detergent oil or his engine will explode. I know that sludge oil is wearing down his engine in a big hurry, not to mention it is full of sludge. the engine is a 4 cylinder original 25,000 mile survivor. I say clean out the engine and use 10w40 Amsoil oil and enjoy the new found power and smoothness, but my buddy says the MANUAL calls for non detergent oil! I want to slap this guy!