Bel-Ray Thumper 4-Stroke Racing Motor Oil is a premium multi-grade synthetic blend motor oil engineered specifically for single cylinder multi-valve 4-Stroke racing engines requiring maximum wear protection of valve-trains, rings, cylinders and pistons.
Bel-Ray Thumper’s special mineral oil-ester blend maximizes ring seal and reduces friction under high temperatures for enhanced engine power over conventional oils. High-performance polymer ingredients provide unbeatable shear stability which protects against viscosity breakdown.
Simply put, this is the best stuff you can put in your engine, period. Bel-Ray Thumper is offered in SAE Grades: 10W-40 and 20W-50 and in 1 and 4 liter bottles.