Automatic transmission fluid is commonly called ATF, with brands like MERCON or ATF Dexron. These fluids have series numbers from II through VI, where VI is intended for the latest transmission units. Mixing fluids is permissible under a simple rule: you can add newer fluid with the highest number to an older one with a lower number, but not the other way around.
The selection is often straightforward because these fluids are not identified by a viscosity grade like engine oils. However, several manufacturers require using fluids that are specific to their brand. For example, Honda may prefer ATF-Z1, while Toyota might specify ATF WS.
Vehicles equipped with Jatco CVTs use NS2 or NS3 fluids. The numbering reflects recency in this system as well: newer models call for higher numbers.
What fluids are used in variators?
Automakers prohibit mixing fluids for automatic transmissions and CVTs. Each CVT maker uses its own distinctive fluid. If a leak arises from the variator cooling system, it is wise to carry a refill container for long trips and to address the leak before a journey. It is important to check the fluid level accurately, with the vehicle on a level surface and the temperature of the variator matching the manufacturer’s recommended range.
What fluids are used in robot gearboxes?
Most dual-clutch robot gearboxes feature two separate chambers. The gear side requires standard gear oil, while the steering or hydraulic chamber uses a special hydraulic fluid. In this setup, only original fluids should be used. For single-link robot boxes, the operating fluid requirements align with those for mechanical gearboxes.
What fluids are used in manual transmissions?
Manual transmissions typically rely on GL-4 oil with a low viscosity such as 75W-80 or 75W-90. Mixing oils from different manufacturers is acceptable provided the viscosity index and GL-4 specifications are respected. Using GL-5 is discouraged for manual transmissions because the additives can harm synchronizers.
Distributors and gearboxes
Some transfer cases in all-wheel-drive vehicles require a specific oil type. For example, certain models like Hover H5 need ATF fluid, and mixing fluids is not advised. Hypoid gears should be lubricated with GL-5 oil. Some crossovers only need a small amount of oil in the front gearbox, such as about 250 ml for certain models like Renault Duster.
Hypoid gearboxes appear not only in large SUVs but also in other four-wheel-drive platforms. A typical setup includes two hypoid gear pairs, one in the rear and one near the front gearbox. These units use oil with a higher viscosity than that used in light manual transmissions, commonly 75W-140. Proper viscosity is essential when adding oil to these gearboxes.
Power steering
Automatic transmission oil is frequently used in the power steering system. If a leak occurs, topping up with ATF helps protect the power steering pump from dry wear and maintains smooth operation.
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