13. Can the A-4 use unleaded regular gas, or should a lead substitute additive be used with the unleaded gas?

The A4 does very well on unleaded gas, and we have never felt that it needs any lead substitute additives. We continue to recommend the use of Marvel Mystery Oil in the gas tank. Follow the recommendations on the can unless you already have any symptoms like sticky valves, and then double the recommendations on the can. - Updated: November 4, 2003