All the manual shows is to check the oil level at least every 2 years. "All 4 jacks should be completely retracted to horizontal position. Oil reservoir is part ogf the pump/manifold assembly. The oil level is checked and filled through the breather cap. The oil level should be within one inch of the top of the reservoir. Most breather caps have a dipstick." It also notes HWH Specialty Hydraulic Oil is recommended, but Dexron automatic transmission fluid can be used. Do not use brake fluid or hydraulic jack fluid--damages the seals. It says if the jacks are dirty with caked on mud, they should be washed. Also, just found this: "The jack rods should not be wiped and do not need to be oiled or sprayed with anything."