k you trail beast, the sticker on the widshield states 'synthetic' but I was having my doubts as to possible leakage, and the car does have small leakage. I appreciate your advice and will have the oil changed to Valvoline which I was told is the best for my Imperial. It is a survivor with only 63,040 origional miles and an 8 1/2 to 9 out of 10, I want to keep it that way. Thanks again, Bob