Burning 1 quart of oil in 500 miles is terrible! I agree that Pennzoil Long Life 15W-40 should help reduce oil usage. I would also suggest using AutoRx at the same time. If using a 15W-40 oil and or using AutoRx doesn't help much then I would suggest using a 20W-50 oil. 20W-50 is very thick however for such a high rate of oil consumption I would use it if the 15W-40 does not cut his oil consumption to less than 1 quart per 1,000 miles.
Any API SL/CI-4 15W-40 "diesel" oil should help to clean out any crud in the motor. However it may be necesary to change the oil filter or even the oil and filter after about 1,500 miles if this engine has been neglected and has a lot of sludge or varnish build-up. After the second oil change with an API SL/CI-4 oil he should be able to go 5,000 miles or longer between oil changes.
[ December 26, 2003, 10:26 AM: Message edited by: Sin City ]