Changing manual gearbox oil

Part 1. Preparation and safety

Objective

• Change the lubricant in a manual gearbox or transaxle.

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

• Work clothing - such as coveralls and steel-capped footwear
• Eye protection - such as safety glasses and face masks
• Ear protection - such as earmuffs and earplugs
• Hand protection - such as rubber gloves and barrier cream
• Respiratory equipment - such as face masks and valved respirators

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

• Do not put your finger into the filler plug opening to check the fluid level whenever the transmission is rotating.
• If the vehicle has been driven just prior to checking the fluid level, the fluid could be very hot. When you remove the filler plug, the hot fluid may run out. Be careful not to burn yourself.
• Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.

Points to note

• If the vehicle is not level when taking a reading, you could get an inaccurate result.
• Selecting and using the correct type and grade of lubricant is critical. The wrong lubricant can lead to premature failure of the internal components.

• A correct fluid level is critical to effective and efficient operation. If the level is too high, the fluid will churn and aerate, causing air bubbles that can trap heat and allow the fluid to run hotter. This can lead to early failure of bearings or gears.
• A low fluid level can cause as much of a problem as a high level. Air can enter the system and heat generation can result in the burning of vital internal components.

Part 2: Step-by-step instruction

1. Prepare to drain lubricant
   Warm up the transmission fluid by idling or driving the vehicle. Raise the vehicle, and ensuring that it is level and stable, do a visual inspection for leaks from the transmission. Most transaxles have drain plugs fitted to them that are easily accessible. However, some require that a housing be removed in order to drain the oil. Other types do not have drain plugs, and require a suction pump to draw out the lubricant by hand from the filling point. Consult the shop manual for correct procedures for draining the fluid on the vehicle you are working on. Be careful because the lubricant can be hot enough to burn.
2. Drain lubricant using drain plug
   Locate the position of the drain plug and remove any guard covers if necessary. Select the correct wrench and loosen the plug. Position a large diameter drain pan under the transmission, clean the plug and then remove it. After the lubricant is completely drained, clean the drain plug. Put the drain plug back with a new washer. Use a torque wrench to make sure the torque is correct.
3. Pump in new lubricant
   Check the shop manual’s lubrication guide for the correct replacement fluid specification and the correct quantity. If the filling location is under the hood, you will need to lower the vehicle. Clean the nozzle of a lubricant pump with a clean lint free rag or paper towel. Use the pump to put new transmission oil into the filler hole or dipstick tube opening. Pause for a few seconds after each pump, to give the lubricant time to flow to the bottom. Stop when the lubricant reaches the bottom of the filler plug hole, or to the top of the cold mark on the dipstick.