I have a 1993 simplicity sunstar garden tractor, sporting a kohler command 20 engine. it has 621 hours on it, not many for a well maintained engine, unfortunately until i got it, the engine was run with cheap oil and poor grade gas. after buying the tractor i added premium gas and that helped, the previous owner changed the oil before i got it, using super tech oil, the worst of the worst. when i would cold start the engine in 0 degree weather, it smoked and sounded labored, as if it was under load when it wasnt. after changing to royal purple 10w30 the difference is night and day. it starts in a quarter of the time (about a tenth of a second) than with the cheap oil and runs smoother and much much cooler. soon im going to change the ATF in the rear axle of the machine with royal purple ATF for maximum performance. THANK YOU ROYAL PURPLE FOR YOUR WONDERFUL PRODUCT.