For normal cars, and light trucks I recommend the Series 2000 0W30, or normal Synthetic 10W30
For classic high performance, and very high performance cars I recommend Series 2000 20W50

For other recommendations contact me at Shriverperform@aol.com

The "Series 2000 0W30" oil is formulated for 35,000 mile/once a year changes, with a filter change at 12,500 mi, or 6 months.
The "Series 2000 20W50 Racing Oil" is good for 3-4 times the manufacturers (of engine) suggested drain intervals, or one year.

Regular synthetic is good for 25,000 mi or one year.

*These recommendations vary by car, please inquire for the proper drain         interval for your application*