100% Synthetic Ester 2T Engine Oil Bel-Ray H1-R Racing 100% Synthetic Ester 2T Engine Oil is formulated for all power valve 2-stroke engines. Advanced 100% synthetic ester base oils cling to metal, preventing wear in all 2-stroke applications. Bel-Ray H1-R Racing 100% Synthetic Ester 2T Engine Oil is clean burning to prevent carbon build-up in combustion chambers and power valve mechanisms. Not suitable for methanol fuel.