Best Way To Check And Refill Gearbox Oil in a Truck

Wondering how to check and refill gearbox oil in a truck? The engine and the transmission system are composed of metallic parts. It is the movement of these metals which makes the wheels of your truck move. The most important part of your truck is the gearbox. The gearbox has various gears made of metals. The gearbox needs oil to function smoothly. 

Overview Of Gearbox oil

The gearbox oil lubricates the transmission system. The primary role of the gearbox oil is to lubricate the gears and ensure that the entire transmission system is running smoothly. The gearbox oil protects the internal part of the transmission system from tear and wear, which can damage them with time. If the level of your gearbox oil is low, the moving metallic parts of the transmission system will not be able to receive adequate lubrication, and this might damage such parts.

Various factors result in the reduction of the levels of the gearbox oil. When your truck has less gearbox oil, you will feel the gears jerking, and gears will slip, shifting problems, as well as strange noises. The gearbox oil should not drastically drop below the required levels. If such happens more often, consider checking for leakages along the transmission system. 

How To Check and Refill Gearbox Oil in a Truck

Never let your truck run on low gearbox oil. To ensure that the levels of oil in your transmission system are standard, do the following to check and refill your gearbox oil.

  1. Park your truck on plain ground and engage the handbrake. The gear lever should be neutral or parking. Start your engine and let it run to warm the oil to enable you to get the current dipstick readings.
  2. As your engine runs, open the bonnet and locate the dipstick. You will find it in the rear compartment of your engine. In some trucks, you will see the filter plug, which functions as an oil level dipstick.
  3. Pull the dipstick out carefully because the oil might be hot, then wipe it. Reinsert the dipstick and then remove it to read the marking of oil at the end of the dipstick.
  4. The dipstick has lower and higher markings showing the gearbox oil levels. The level of oil should be close to the upper mark.
  5. Observe the color of your gearbox oil. Healthy gearbox oil should be slightly red and not have any burning smell. If it is dark, consider changing it.
  6. If your oil levels are low, use a long neck funnel and refill the recommended gearbox oil up to the recommended levels. Do this with the dipstick inside to enable you to determine the proper levels of oil. You should not refill the oil beyond the recommended mark. 
  7. Remove the funnel together with the dipstick. Check if the levels of the oil are okay. Insert the dipstick and close your bonnet.


Gearbox oil is the backbone of your gearbox. To give your truck long life, consider checking the levels of this oil regularly and topping it up whenever it is low. Shared in this guide is how to check and refill gearbox oil in a truck. Checking the oil will enable you to determine whether it is healthy.

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