I can't speak for all brands of synthetics, but I can state that the one I have been using and selling for 26+ years has 4 times the film strength of a similar weight petroleum oil. There is a series of tests that prove the superiority of synthetics over the petroleum oils in the lab every time, and it is the four ball wear test ( ASTM D 4172 B) and the shear viscosity test ( ASTM D 4683 ).
How an oil quickly pours has nothing to do with film strength of the oil.
The old wives tales about multi grade oils being inferior stem back to the 50's when they were inferior. The light portions of the oil were more volatile and would vaporize to quickly in heavy load industrial applications leaving the operator with sludge in the crankcase. By the 70;'s, the oil companies were forcet by the engine manufacturers to improve all multi grade oils which they did by adding better quality base stocks to their blends which virtually eliminated that problem, for a while.
Synthetics characteristicly have a flash point ~ 100 degrees higher than petroleum oils, a pour point approximately 30-40 degrees lower than petroleum oils, and are much less volatile.
Synthetics are better, but some are better than others. The major brand name on the bottle may not be an indication that it is the best synthetic oil.
The synthetic I am familiar with, will give you between 6% and 10% more horsepower on the dyno, or approximately 300 more rpm in a boat at full throttle, not to mention easier starting, less plug fouling, less wear, cooler operation and longer engine life.
Bob
