For Hsb Models Made Before 2013, Use The Generac 5665 Air Cooled, 999Cc Kit. Scheduled maintenance is a necessity for all standby generators. The Air-Cooled Scheduled Maintenance Kits offer all the components necessary to perform a complete maintenance on Generac air-cooled generators. Maintenance is recommended at every 200 hours or 2 years. If running in a dusty environment, more frequent maintenance may be required. Generac Guardian Maintenance Kit for 20kW Home Standby Generators Tune-Up Kit, Keep your generator running at optimum performance Contents: Air Filter, Oil Filter, Oil Funnel, Spark Plug, Chamois, Instruction Manual, Reminder Sticker (2008 to 2012) Includes: air filter, oil filter, spark plugs,oil funnel, chamois Oil must be purchased separately Includes: air filter, oil filter, spark plugs,oil funnel, chamois Oil must be purchased separately