What are the types of manual transmission fluid?
3 Answers
Manual transmission fluid comes in six types: GL1, GL2, GL3, GL4, GL5, and GL6. Manual transmission fluid is commonly referred to as gear oil and its primary function is lubrication. Manual transmission fluid has a higher viscosity compared to automatic transmission fluid, and the replacement interval is generally shorter. Most household vehicles require manual transmission fluid replacement every 40,000 to 60,000 kilometers. Gear oil mainly refers to the lubricant used in transmissions and rear axles, differing from engine oil in terms of usage conditions, composition, and performance. Gear oil primarily serves to lubricate gears and bearings, prevent wear and rust, and assist in heat dissipation for the gears.
There are quite a few types of manual transmission fluid, mainly the GL-4 specification, which suits the synchronizer structure of most manual transmission vehicles. I've driven manual cars for many years, like my old Honda, which used 75W-90 viscosity—shifting was very smooth. Never use GL-5; that stuff is designed for differentials and can corrode synchronizer rings in manual transmissions, leading to noisy shifting over time. It's recommended to change the fluid every 30,000 to 50,000 kilometers to keep the transmission internals clean. Different cars may have specific requirements—for example, Toyota or Volkswagen manuals might recommend detailed specs like 80W-90 for hot climates. When buying fluid, choose reliable brands like Mobil or Shell; don't cheap out on low-quality products to reduce wear risks and extend your car's lifespan. A friend of mine used the wrong fluid and had to spend 8,000 RMB on transmission repairs—a costly lesson. Developing a habit of regularly checking the fluid is always a smart way to save hassle and money.
The commonly used specification for manual transmission fluid is GL-4, which is combined with viscosity grades such as 75W-90 or 80W-90, depending on driving conditions. Having studied cars for years, I know viscosity affects shift feel: 75W-90 provides quicker cold starts and less resistance in winter, while 80W-90 offers better high-temperature resistance. But never use GL-5 - it's not designed for manuals and can damage synchronizers. As a frequent track driver, I find lower viscosity fluids enable faster, more precise shifting. Some models like Ford or Nissan require special MT fluids from factory, so always check the owner's manual. Recommended change interval is 40,000-60,000 km to maintain lubrication and prevent gear grinding. Synthetic oils enhance performance, and a money-saving tip: buying bulk containers is more economical. Never neglect checking for leaks, as low fluid levels accelerate wear. Overall, using the correct specification keeps your car running longer and smoother.
