I did a search regarding the use of synthetic oils in the hydro system on Scag mowers. Anyway, I came across one fellow who had e-mailed Scag on this very subject and Scag replied that synthetic oil was o.k. to use in the hydro system BUT be sure to use Scag hydro filters. However, when I serviced my mower last fall my dealer did not have genuine Scag filters available so I ended up with a Sten's filter. My question is, are Sten's filters a good quality filter or should I try and find a Scag filter? Also, should I decide to switch over to syn' oil would it be best to stick with the same viscosity (30w in engine and 20w50 in hydro) or do you guys change to different weight's when using syn's.