Originally Posted by strafen
Being a car nut myself, I feel I'm somewhat qualified to offer a couple of helpful tips.
1- If your car has high-mileage and leaks a little bit of oil, DO NOT attempt to use synthetic oil. The synthetic oil will find a way to seep thru that "little" leak and make it worse.
2- High-mileage cars tend to have worn-out seals, along with the crankshaft bearings having an increased tolerance. You don't want to use synthetic oils in that case
3- The most popular synthetic oils such as Mobil-1, Valvoline, Penzoil, etc...can be purchased a lot cheaper if you buy by the 4-qrt containers as opposed to buy it by the quart.
Best synthetic oils out there in no particular order:
-Schaeffer's Synthetic Oil
You for got Castrol and Redline sucks! Your #2 is dead wrong. If you have worn bearing or bad valve guides just move up to a 20-50 or straight 30w. You can then still use syn. and have way better protection without the burn off.