My 3510 is ready for it's 30 hour fluid changes. My manual says to use THF 500 in the transmission. What is THF 500? Can anyone out there please advise the proper fluid? I know very little about hydraulic fluid grades and what works where. I do know there are a wide variety of price ranges. Please do not recommend high end expensive fluids like AMSOL. I can't pay $200+ for an oil change. You help would be truly appreciated. Info on filters would be welcome also. /forums/images/graemlins/confused.gif