On Feb 10, 2008, at 1:17 PM, William Robb wrote: >> I think the 10W/40 is a good choice for the Volvo. Remember that >> clearances open up as the engine wears. That oil is probably a bit >> heavy for the Sprite if it doesn't have a lot of miles. I'd use the >> 10-40 synthetic in that as well. I use 5w-30 Mobil 1 synthetic in my >> 55 Chevy, but the engine was rebuilt 20,000 miles ago with >> contemporary bearing, valve guide and piston skirt clearance. > > As an addition to this discussion, I was told by my cousin the > petrochemical > engineer (he headed up the design team for Royal Dutch Shell that > created > unleaded gasoline, and then later CFC free styrofoam, of all > things), that > from a user point of view, the difference between conventional > motor oil and > synthetic is that conventional oil, no matter how well refined, has > waxes in > them which coat the bearing surfaces when cold and impair > lubrication out > until it melts back into the oil. Synthetic oil, being sourced from > natural > gas, doesn't have this problem. I suspect that if you live in a warm > climate, synthetic oil is rather a waste of money, since it will > never be > cold enough to harden out these waxes.
A short article on oil and oil technology written by my buddy and motor savant, Dr. Ed Hackett PhD (Chemistry), about 14 years ago. http://www.off-road.com/offroad/article/articleDetail.jsp?id=290242 Godfrey -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
