Bel-Ray Si-7 Synthetic 2T Engine Oil Bel-Ray Si-7 Full Synthetic 2T Engine Oil is a 2-stroke motorcycle oil specifically formulated for use in injector/autolube systems, but can be used as pre-mix. Formulated to reduce smoke and carbon residue while providing the highest level of protection for all 2-stroke engines. Bel-Ray Si-7 meets the JASO FD and ISO-L-EGD ratings ensuring the highest level of detergency for better performing, longer running engines.