February 5, 2010 2:11 AM PST
Lots of good info except what Synthetic oil is. It's manufactured in a lab.
Say you take one drop of Dino and one drop of Syn, look at them under a microscope, the Syn molecules will all be the same diameter, say 1/2 inch balls. The Dino molecules will vary from 0-1 inch diameter balls, this is what makes Syn oil lube better, it's consistant size. Engineers this past decade have used this fact to create tighter tolerance designing engines, thats why you see factory recommended oil viscositys at 5-20 and 10-30 for most newer engines recomending Synthetic oils. Many new vehicles come new with it in the engines.
I have researched this topic to death the past few years and found equal arguments on both sides of the fence, some say Synthetic oil is too slippery for new engines, it won't allow rings to seat in properly and say wait a couple thousand miles before using it. Others disagree, it's a fact some new motors come with it already. Personally I use recomended Honda standard 10-30 and change it every 1500 miles, there's no substitution for clean oil. The reason I change it so often is my engine spins 10000 rpms and I run the shit out of it on occasion. If I had slower engine I would go more miles on the oil.
Some want to use thicker oil, 20-50 instead of recomended 30 or 40 weight, my feelings are this. The viscosity is determined by engine clearance, main bearings, piston / cylinder clearance, ect ect. Say the factory recomends 40 weight oil and you put fifty weight in it. Try a little experiment, set a spark plug gap at .040, now cram a .050 feeler guage into the gap........... thats what you are doing using a thicker oil, you CAN cram it in there but you are forcing it causing more friction to do so.............