On 1994 vehicles equipped with a Borg Warner 5 speed manual transmission, use Dexron® II automatic transmission fluid. On 1995 vehicles equipped with a Borg Warner 5 speed manual transmission, use Dexron® III automatic transmission fluid.
On 1994-99 vehicles equipped with a New Venture Gear 3500/1500 and 1996-97 Borg Warner 5 speed manual transmission, use Synchromesh transmission fluid GM part No. 12345349 or its equivalent.
Using the incorrect lubricant in your transmission can lead to significant transmission damage and a costly overhaul.
See Figures 1 through 5
Remove the filler plug (usually with a 17mm Allen wrench) from the side of the transmission (usually located on the passenger's-side of the housing). If the transmission housing contains 2 plugs, the lower is a drain plug, while the upper plug is the filler. The oil should be level with the bottom edge of the filler hole. This should be checked at least once every 6000 miles (9600 km) or if leakage or seepage is observed. If the oil level is below the bottom edge of the filler hole, add the recommended lubricant until the proper level is reached. Most parts stores will carry a small, hand operated pump which will greatly ease the task of adding fluid to the transmission.
When checking the fluid, the vehicle must be level. If it was necessary to raise and support the vehicle to access the filler plug, the vehicle must be supported at sufficient points (all wheels or 4 points on the frame) so it is sitting level and is not tilted forward/backward or to one side.
DRAIN AND REFILL
See Figures 6, 7, and 8
Under normal conditions, the manual transmission fluid should not need to be changed. However, if the truck is driven in deep water (as high as the transmission casing) it is a good idea to replace the fluid. Little harm can come from a fluid change when you have just purchased a used vehicle, especially since the condition of the transmission fluid is usually not known.
If the fluid is to be drained, it is a good idea to warm the fluid first so it will flow better. This can be accomplished by 15-20 miles (24-32 km) of highway driving. Fluid which is warmed to normal operating temperature will flow faster, drain more completely and remove more contaminants from the housing.
- Raise and support the vehicle safely using jackstands.
- Place a fluid catch pan under the transmission.
- Use a rag to clean any dirt from around the fill plug and the drain plug.
- Remove the filler plug (usually with a 17mm Allen wrench) .
- Remove the drain plug (usually with a 17mm Allen wrench) from the bottom of the transmission housing and allow the fluid to drain.
- After all the fluid has drained, install the drain plug. Before installing the drain plug on 1997-99 models, apply Teflon® sealer GM part number 1052080 or its equivalent to the plug threads.
- Refill the transmission with the specified type of fluid until the fluid is level with the filler hole. Most parts stores will carry a small, hand operated pump which will greatly ease the task of adding fluid to the transmission.
- Install the filler plug and lower the vehicle.