There is a seal on every quart of oil that gives its classification. Look at the first set of letters. "S" is for spark plug ignited engines and "C" is for compression ignited engines. Obviously get an oil with the C rating. Other letters in the seal are not as important but you should use a 30 wt oil. Also, buy one of those containers with a pump that suck the oil out of the dip stick hole. Good luck. walt walterts@aol.com