I just got back from a business trip to Montreal (beautiful city, beautiful women!) and when I grabbed the cab from the airport, I noticed that this Malibu had quite the noisy engine. It was ticking noticeably at idle, and even louder when moving. Being the oil freak that I am I couldn't help but wonder what oil he was running. I got my answer when I arrived at the hotel! When he opened the trunk to get my bag, I saw a bottle of Castrol GTX 20w50! I guess that thick oil isn't so great for engine longevity after all is it? In all fairness, I didn't see the mileage on this cab, so who knows, it could have had 500k for all I know.