A myth started a long time ago that if your vehicle does not require full synthetic oil, but is put into the engine it can never be switched back. If you'd like to hear the whole story I would love to tell it.
Suffice it to say, full synthetic oil benefits all engines not just high performance models in extreme conditions. I do not recommend it for every car, though it is beneficial in extreme temperature environments, heavy towing or as it is intended, high performance vehicles. It is completely okay to stick with regular grade if that is all it calls for and is changed regularly.
Your second query, are some synthetics better than others? The most important thing you should know is that synthetics have no crude oil, oil that originated from the ground, at all. But to the point, No. All synthetic oils perform within a close tolerance of the other, provided it has the American Petroleum Institute (API) stamp on it.
Mobil 1 and Pennzoil full synthetics do flow well at very low temperatures and thicken well under extreme stress; however, unless you live in the tundra or race on weekends there is no discernable advantage to a synthetic oil over crude.
One last note, if you vehicle manufacturer recommends a synthetic, blend or manufacturer, always follow it to keep the warranty valid. Most manufacturers offer at least an 80,000 mile powertrain warranty.
You can read the official consumer report at this website.
Tuesday, November 17th, 2009 AT 10:26 PM