I would beware of changing over to synthetic oil... Its extremely good oil and very efficient, but if the car has 100k or so, I'd think it out before putting it in the motor... Synthetic is much much thinner, working at Advance for three years, I seen a lot of people switch and a lot of them coming back fussing about the motor pouring oil around the seals... Seems like it finds its way out of those dated seals and it really causes a problem... Just some food for thought... Good luck... But I would probably be in the AmsOil boat myself if I was going to use it... Very expensive, but tested many times showing the best results