WHAT WOULD BE THE PROPER FLUID TO PUT IN THESE HYDRAULIC SHOCKS. JACK OIL , LIGHT WGT SYNTHETIC OIL OR SOME THING ELSE.?

HYD. SHOCK OIL Dan - I use hydraulic jack oil in the lever shocks on 1929 - 34. I have also used motorcycle fork oil because it is available in different weights and I could tailor the weight to the condition of the shock. If the valves were worn, a heavier fork oil could be used. Motor oil is simply too heavy and is not suitable as a shock oil. I'll ask a shock rebuilder what he uses and pass it on as well. tom April 1, 1999 ANSWER: HYD. SHOCK OIL Regarding proper oil for hydraulic shock absorbers on the 1929 - 1934 Franklins: I talked to Bob at Apple Hydraulics (an excellent shock absorber rebuilding company) about proper oils to use. He said that motor oil is strictly prohibited because the detergents will eat the shock absorber seals. He also expressed concern about corrosion due to oil acidity. I do not believe corrosion would be a problem, but the detergent definitely is. Automatic transmission fluid is a more highly refined oil, but also contains high detergents which will ...  more