Toro's residential zero-radius-turn mowers require an oil change after the first eight hours of service, after the first 50 hours of service and then after every 100 hours of service for the life of the mower. For these oil changes, choose a good quality detergent oil of an appropriate viscosity.
Toro specifies that 1.9 quarts (2.2 quarts when the filter is changed) of a detergent oil with an API service rating of SF, SG, SH, SJ or SL be used when changing the engine oil in their residential zero-turn-radius mowers.
Determine the proper oil viscosity by anticipating the temperature range of the mower's environment until the next oil change. Temperature ranges below 32 degrees Fahrenheit require SAE 5W-20 oil. Temperature ranges from zero F to about 95 F require SAE 10W-30 or SAE 10W-40 oil. Temperature ranges between 32 F and 95 F require SAE 30 oil. Temperature ranges between 70 F and 100 F require SAE 40 oil. When using multi-grade oil, check the oil level in the mower more frequently, as multi-grade oil increases oil consumption.