14-15lbs at speed and 6-7lbs at idle when warm. #20 or #30 oil is fine for your engine or a 10w-30 multigrade mineral or synthetic.
At 3-4lbs I would suspect worn main or cam bearings. You might get by for a while by adjusting the main bearings.
DG

Last edited by Denny Graham; 11/30/2010 2:12 PM.
Denny G
Sandwich, IL