What are the specifications of transmission oil?
3 Answers
Manual transmission oil, also known as gear oil, is divided into five grades: GL-1 to GL-5. Here is the relevant information: 1. Manual transmission oil, commonly referred to as gear oil, is primarily used for lubrication. The American Petroleum Institute categorizes vehicle gear oils into six classes based on performance: GL-1, GL-2, GL-3, GL-4, GL-5, and GL-6. Among these, GL-1, GL-2, and GL-3, which are more suited for heavy-duty applications, have been phased out in the market. Currently, household vehicles typically use GL-4 and GL-5 (GL-6 is used for buses). 2. In terms of oil characteristics, the most noticeable difference is that manual transmission oil has a higher viscosity compared to automatic transmission oil, and the replacement interval is generally shorter. Most household vehicles require manual transmission oil replacement every 40,000 to 60,000 kilometers. 3. The main types of transmission oil currently used in China include DEXRON, DEXRON-II, and DEXRON-III (produced by General Motors), ATF-F (produced by Ford), as well as domestically developed No. 8 oil (mainly used in various passenger car hydraulic automatic transmission systems) and No. 6 oil (primarily used in the hydraulic torque converters of locomotives and heavy-duty vehicles).
When helping a friend choose transmission fluid recently, I realized how complex it is. For automatic transmissions, American cars mainly follow certifications like Dexron and Mercon, while Japanese cars have their own specifications such as Toyota WS and Honda DW. European cars are even more complicated—Volkswagen's G-series certifications are divided into codes like G052 and G055, and Mercedes and BMW require matching transmission models. Manual transmissions are relatively simpler, with GL-4 and GL-5 being the most common viscosity standards, but those with torque converters need extra attention. Don’t blindly trust universal products—last time, a repair shop used non-WS-standard fluid in my old Camry, resulting in noticeable cold-shift jerks. The most reliable approach is to check the maintenance manual and strictly follow the certification codes listed there.
As a professional who works with transmissions daily, selecting transmission oil starts with three main categories: AT (Automatic Transmission) fluids are dominated by Dexron VI (for 6-speed and above) and Ford Mercon LV; CVT fluids such as Nissan NS-3 or Subaru Lineartronic-specific oils; and for dual-clutch transmissions, there are low-viscosity products like Volkswagen DCTF. Mineral oils are mostly used in older manual transmission vehicles, with 75W-90 being a common grade, but GL-4 offers better copper compatibility than GL-5. Extra caution is needed with the newly introduced DF transmission fluids, as the electric pumps in hybrid vehicles have stringent requirements for conductivity. Avoid cheap, no-name brands—substandard oils with sulfur-phosphorus additives can corrode synchronizer rings.
