</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Synthetic oils will leak from an engine that did not leak with conventional oil though! </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Are you talking from experience or just spreading rumors? I have used synthetic oil since 1976 and it has never caused any leak.

Synthetic lubricants do have an inherent detergency that cleans and removes conventional motor oil deposits left over in an engine. However, motor oils are designed to help swell seals slightly to prevent leakage. The only time you would observe seal leakage is if the seals are already damaged or showing signs of leakage around them. As long as the vehicle has been well maintained, and in good mechanical condition, it can be switched to a synthetic lubricant at any mileage.