Synthetic Oil is a superior engine lubricant. All the lubricant particles are uniformly shaped unlike conventional oil. However there are some things you should know. Synthetic Oils are produced in one of two ways. The first way is expensive and produces a superior product. Mobil 1, Royal Purple and Redline use this expensive process. The second method is much cheaper and all other synthetic oil manufacturers use this cheaper method. The second thing you should know is that synthetic oil is more slippery and seeps thru any poorly fitting gasgets and seals in your car. For this reason, it is best used in newer cars. When synthetic oil is used in older cars, the hardened gasgets will tend to leak more oil. I have used Mobil 1 with great results for 25 years and all my cars have gone 200,000+ miles without problems. When they start to leak oil (usually at 140,000 miles) I switch to conventional motor oil because it leaks out less. This transition is does not cause any problem like a prior poster suggests. I have never used any "synthethc blend" oils since they defeat the prupose of synthetic oil alltogether.