I'd also reccomend 20W-50 as the extra physical thickness of the base weight oil will translate into better oil pressure. The oil flows like a 20 weight when cold, and lubricates like a 50 weight when hot. It stays the physical thickness of a 20 the whole time- - - -it does not thicken up as it heats up. Trying to hold oil pressure with what amounts to 10 weight when hot is a losing battle. Originally, these engines were intended to run straight 30 weight in the summer, and 20 or thinner in cold weather for better cold-start lubrication. 15W-40 diesel-rated oil is also another good choice, as there are some zinc compounds in it that help keep the camshaft lobes in good shape.
Jerry

Last edited by Hotrod Lincoln; 12/22/2008 12:36 AM.
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!