Q: How to perform a transmission fluid and Transmission Filter replacement on Chevrolet Avalanche,Silverado,Suburban,Tahoe and GMC Sierra,Yukon,Yukon Denali,Yukon XL?
A: Always at the designated maintenance intervals, there should be a changing of transmission fluid. However, do not commence until the engine is completely cooled. Begin by getting a fresh pan gasket, new filter and transmission fluid. The tools to have include drain pan with sufficient capacity, clean rags, newspapers, jackstands for secure vehicle support, floor jack and others. Elevate the vehicle and secure it on jackstands if pan removal is obstructed by exhaust system front section. Underneath the transmission pan have a drain pan in position, remove drain plug (if available), allow fluid to drain till trickling stops and then replace the plug again. Remove bolts from three sides of the pan if there's no drain plug; loosen the remaining ones slightly and lower the pan to get rid of most of the fluid in it. Then remove bolts carefully lower the pan and let out all the remaining fluid in it. Remove heat shield close to catalytic converter on right hand side to access pan bolts. On driver's side, for accessing pan bolts remove shift linkage. Undoing transmission pan mounting bolts with screwdriver gently pry off the pan. Clean up gasket surface thoroughly on transmission to get rid of any leftover old gasket or sealant materials thereon.Turn off your vehicle and disconnect 12V battery negative terminal.New one must be fitted while referring to diagrams & instructions given by manufacturer as this cannot be done any other way.Make sure that new gasket is attached to clean transmission pan's gasket surface before placing back onto transmission & tightening all bolts.Refer to powertrain control/emissions diagnosis manual for proper diagnostic steps.Remove heat shield close to catalytic converter on right hand side to access pan bolts.Do not drive anymore; rather shift lever will stay put at any chosen gear.The power from engine has been evenly distributed through five gears but only one is used at any given moment.Clean up gasket surface thoroughly on transmission to get rid of any leftover old gasket or sealant materials thereon. This must be done with the engine running at fast idle speed, transmission in Park and cycling through each gear position back to Park before returning to idle.Thus the fluid level will be low and it will have to be added until it reaches the mark on the dipstick but without overfilling.Turn off your vehicle and disconnect 12V battery negative terminal.New one must be fitted while referring to diagrams & instructions given by manufacturer as this cannot be done any other way.Make sure that new gasket is attached to clean transmission pan's gasket surface before placing back onto transmission & tightening all bolts.Refer to powertrain control/emissions diagnosis manual for proper diagnostic steps.With the engine running at a fast idle and the transmission in Park, cycle the gear selector through each range and back to Park before letting the engine idle.Tighten each bolt gradually to the specified torque. Reinstall components removed for pan bolt access, lower the vehicle, and add about 4 quarts of the specified automatic transmission fluid through the filler tube.The above mentioned procedure should be performed every 30,000 miles.As such, the fluid level is likely to be low hence more should be included until it hits line on dipstick avoiding overfilling.Finally look out for leaks beneath vehicle during first trips and when transmission is hot check again its fluid level.