read your owners manual. it will give the makers recommendation on fluid changes. I recommend that you monitor the transmission fluid level about every six months. if the fluid on the dip stick smells burnt, have the transmission flushed and new fluid added. (not just 3 or 4 quarts, flush out all the old fluid) even if the maker specifies extremely long change intervals, I would flush and replace all the fluid at about 80 thousand miles and again at about 130 thousand miles. if the vehicle has over 100 thousand miles and the fluid has never been changed, leave it alone if it is performing satisfactorily. trying to flush a transmission with excessive miles may break loose enough debris to clog the whole system.
