BEL-RAY WORKS THUMPER RACING FULL SYN ESTER 4T 10W-50 (4L), Manufacturer: BEL-RAY, Manufacturer Part Number: 99550-B4LW-AD, Stock Photo - Actual parts may vary. &nbsp;Synthetic ester formula for the ultimate Thumper experience &nbsp;Withstands extreme racing conditions &nbsp;For air-cooled / liquid-cooled 4T engines with wet clutches API SM, JASO MA2