Personally, I purchase the manufacturers recomended lube for my RWS mdl 54. I did "tune" a "Beeman" RS2 though; Heavy black tar grease on the spring, Moly paste on the piston (sparingly) and RWS Air Chamber Lube. I did this for practice, it was my first time. However, the spring did quiet down as expected and it seems to shoot much smoother with no loss of power. Now, if I could just fix the trigger. I did find info on a trigger tune, I'm looking for parts now.