Skip the auto shop - Our mechanics make house calls

How to Buy Good Quality Differential/Gear Oil

Differential/Gear Oil

Gear, or differential, oil is used to lubricate the gears in a car’s transmission so that it can shift smoothly and easily. This type of fluid is generally used on standard transmissions, whereas transmission fluid is used in automatic cars.

Differential oil is extremely high viscosity and can withstand the hot temperatures reached in the gearbox. Over time the level will drop to some extent, however, and you may need to top it off. If you notice grinding or difficulty when shifting gears, check the gear fluid. The gearbox is often located behind – and lower than – the engine, but check your owner’s manual to be sure. It may have just a plug, or there may be a dipstick as well. The oil should come up to the plug hole, allowing you to touch it. If it doesn’t, top it off until the fluid just starts to spill out of the hole.

When shopping for gear oil it’s important to understand both the API (American Petroleum Industry) and SAE (Society of Automotive Engineers) ratings. The API is expressed as GL-1, GL-2, etc. (GL stands for gear lube). This rating relates to the additives in the gear fluid designed to stop metal-on-metal contact between the gears.

SAE ratings are expressed in the same way as with engine oil, for example 75W-90, indicating the viscosity of the fluid. The higher the rating, the thicker it is.

Passenger vehicles typically take GL-4 gear fluid, but check your manufacturer’s recommendations before putting anything into your gear box.

How to make sure you’re getting good quality differential/gear oil

  • Consider a more expensive brand. Differential fluids like Amsoil and Red Line are a bit more expensive than those you’ll find in a big box store but they’ll need changing less frequently.

  • Don’t mix ratings of gear oil. Because of the different additives in the various types, they may not play nice together. Always drain the system first if you’re going to change types.

  • Be aware that differential fluid labeled as GL-4/GL-5 is really GL-5. If your car calls only for GL-4, do not use these “multipurpose” oils.

YourMechanic supplies top-quality gear oil to our certified mobile technicians. We can also service your car with gear oil that you've purchased. Click here to get a quote for a Gear Oil Replacement.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

How to Find the Keyless Code on a Ford Explorer or Mercury Mountaineer
Many Ford Explorers and Mercury Mountaineers were manufactured with an option known as the Ford keyless entry keypad. Some models refer to it as SecuriCode as well. It...
P0121 OBD-II Trouble Code: TPS "A" Circuit Range Performance Problem
P0121 code definition Throttle Pedal Position Sensor/Switch (TPS) A Circuit Range Performance Problem...
P0222 OBD-II Trouble Code: Throttle/Pedal Position Switch/Sensor B Circuit Low Input
P0222 code definition Throttle/Pedal Position Switch/Sensor B Circuit Low Input What the P0222...


Related questions

Q: Code P0720 and truck does not shift normally.

Hi there. The code that you are getting is for the output speed sensor of the transmission. I change quite a few of these as they are a common issue. I would have this replaced first and clear the codes....

Q: Rear end noise, weak acceleration

Hello. A better description of what it sounds like would help me to determine what you need. If you are getting a grinding, growling, or popping noise, then it is more than likely a failing rear differential. These commonly fail...

Q: Burning oil

Hi there. The engine has valve guide oil seals that prevents oil puddling up onto the valve and allowing the valve to suck in the oil. The valve guide seals are leaking too much and causing excessive oil to enter...