----- Original Message ----- From: "Paul Stenquist" Subject: Re: Follow-Up OT: Question for Pentax Auto Buffs Discussion Group
>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. William Robb -- 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.
