How to Check Gear Oil Posted by John Baker, 8th February 2017

It is a good idea to check your vehicle’s gear oil to monitor oil level and condition before the gear oil change is due. Check the oil immediately if the gearbox jerks, hesitates, shifts hard or if the oil is leaking.

The recommended interval to change gear oil varies considerably (15 000 – 60 000 miles) depending on the car make, model and age of the vehicle. We, therefore, recommend consulting your car owner’s manual. Cars with an automatic gearbox will require more frequent intervals for gear oil control and change.

1. Obtaining a correct reading on the dipstick requires the oil to be warm and the engine to be running. To begin, park your vehicle on a flat surface, apply the parking brake and let the engine idle until warm. You may have to drive your vehicle for a short period of time to raise the gear oil temperature. Some original equipment manufacturers (OEMs) also recommend shifting through the gears to circulate the oil prior to checking, so consult your owner’s manual.

2. Pop the bonnet and locate the gear oil dipstick, which typically serves double duty as the fill tube. It’s often located near the back of the engine compartment and shouldn’t be too tough to find. You can always check your owner’s manual for the location if it proves elusive.

3. Pull the dipstick and wipe clean with a lint-free rag. Reinsert the dipstick. Make sure it’s completely seated. Withdraw the dipstick again and check the oil. The dipstick may have a cross-hatch pattern in which the oil level should fall. Others may have a “hot” and “cold” line. The oil should be close to the “hot” line.

4. If the oil is low, add the recommended gear oil to bring to the correct level. You’ll probably need a long-neck funnel with a small-diameter opening at the point.

“Fill-for-life” automatic gearboxes are becoming more popular. Most don’t even have a dipstick for checking gear oil. On those that do, they can be located in hard-to-access areas. In these cases, check a service manual for dipstick location and instructions for checking the gear oil. Although the gearbox is designed to be “filled for life,” it may still require additional fluid from time to time. Also, “fill for life” typically means fill for the life of the warranty. It’s just as important to service these units and replace the gear oil once in a while to ensure the gearbox lasts as designed and gives you years of solid performance.

Which gear oil should you use?

To shift properly and provide years of reliable service, your gearbox requires a gear oil that provides the correct frictional properties. The gear oil also must resist formation of harmful sludge and varnish, which can clog the narrow fluid passages and lead to poor shift quality. This is particularly important if you tow or haul, which increases heat and invites oil breakdown.

AMSOIL formulates a full line of synthetic gear oils that help you get the most out of your vehicle.


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