...Contaminants Change your oil and change it often is the key. Synthetics hold up better to stress and resist breakdown, but in the case of the VX, unless you have some major engine modifications, like SC, etc... Synthetics buy you peace of mind more than anything else. Change your oil every 3000 miles and your engine will thank you, use synthetic if you can afford it for added peace of mind and change it just as often. My 2cents