Phillips 66 Guardol NG 15W40 is a natural gas engine oil that is made for vehicles that have a natural gas engine with slider follower valve trains. It has anti-wear additives that are at a higher level to meet the requirements of diesel engines that have been converted to natural gas.
Transit buses, school buses and delivery trucks with slider follower CNG or LNG engines
Cummins CES 20085
Detroit Diesel DFS 93K216
John Deere 6.8L and 8.1L CNG engines