How to Buy Good Quality Differential/Transmission Oil
Gear or differential oil is used to lubricate the gears in a car's transmission so they can shift smoothly and easily. This type of fluid is commonly used in standard transmissions while transmission fluid is used in vehicles with automatic transmissions.
Differential oil has an extremely high viscosity and can withstand the high temperatures reached in the gearbox. However, over time, the level will drop to some extent, and you may need to refill it. If you notice a grinding noise or difficulty shifting, check the transmission fluid. The gearbox is often located behind and below the engine, but check your owner's manual to be sure. It can only have a cork, or maybe a probe. The oil should reach up to the candle hole so that you can touch it. If this is not the case, add more until liquid starts to pour out of the hole.
When buying gear oil, it is important to understand the API (American Petroleum Industry) and SAE (Society of Automotive Engineers) ratings. API is referred to as GL-1, GL-2, etc. (GL stands for Gear Lubricant). This rating applies to transmission fluid additives designed to prevent metal-to-metal contact between gears.
SAE ratings are expressed in the same way as for motor oil, such as 75W-90, indicating the viscosity of the fluid. The higher the rating, the thicker it is.
Passenger vehicles typically use GL-4 transmission fluid, but check the manufacturer's recommendations before pouring anything into the transmission.
How to make sure you buy good quality differential/transmission oil
Consider a more expensive brand. Differential fluids like Amsoil and Red Line are a bit more expensive than those you'll find at the big store, but will need to be changed less often.
Don't mix gear oil ratings. Due to different additives in different types, they may not be compatible with each other. Always flush the system first if you are going to change types.
Be aware that the differential fluid labeled GL-4/GL-5 is actually GL-5. If your vehicle only requires GL-4, do not use these "universal" oils.
AutoTachki supplies certified field technicians with the highest quality gear oil. We can also service your vehicle with the gear oil you have purchased. Click here for the cost of a gear oil change.
