We’ve discussed the nuances of mixing different fuels, engine oils, antifreeze and brake fluids here.
Fluids for automatic transmissions, CVTs and robotized gearboxes
Automatic transmission boxes use a liquid labeled ATF Dexron or MERCON, and the designation that follows includes a Roman numeral from II up to VI in the latest units. In practice, newer liquids with higher numbers can often be poured into older boxes, but this is subject to manufacturer guidelines.
The good news is that these fluids do not rely on a viscosity rating like motor oil, which simplifies selection. Some automakers have their own preferences, such as Toyota with ATF WS and Honda with ATF-Z1, among others.
For variators, the situation is even clearer. Renault-Nissan vehicles and many others that employ Jatco CVTs typically use NS2 or NS3 fluids, with newer models tending toward higher numbers.
Automakers do not permit mixing CVT and automatic transmission fluids. Each major CVT manufacturer uses its own fluid, so it is best not to mix anything in this system. If a stuffing box or hose from the variator cooling system leaks, it is wise to top up only with the specified fluid prior to a long trip and to address the defect. The level should be checked at a temperature specified by the manufacturer while the vehicle sits on a level surface.
Most robotic gearboxes with dual clutches feature two separate cavities. A special hydraulic fluid is poured into the control system, and other liquids should not be added. In the mechanical section where gears operate, conventional gear oil is used.
Robotic gearboxes with a single linkage oil requirement follow the same rules as mechanical boxes and will be explained further below.
Manual gearbox, transfer case, gearboxes
For manual gearboxes, the common oil choice is a GL-4 grade with relatively low viscosity such as 75W-80 or 75W-90. It is permissible to use oils from any manufacturer, but the viscosity and GL-4 quality level must be checked to avoid issues. It is discouraged to use GL-5 oil in a mechanical box because additives can harm synchronizers.
Transfer cases in some cars require gear oil, such as in domestic four-wheel drive models. In other vehicles, exemplified by Hover H5, ATF fluid in the transfer case is appropriate, and mixing should be avoided.
Gearboxes with hypoid engagement require GL-5 oil only.
The front gearbox in many crossovers holds a small oil volume; for instance, Renault Duster contains about 250 ml. Hypoid gearing appears not only in rugged off-road axles like those in UAZ and Toyota Land Cruiser but also in some crossovers such as Crete. In these units two hypoid gear sets may be present, one in the front gearbox and one in the rear. In such cases the oil viscosity is higher than in mechanical boxes and can reach 75W-140 in heavily loaded units, ensuring the use of hypoid oil with the correct viscosity remains essential.
Exotic drips
The drive supercharger is another area that requires oil and periodic changes. The practice calls for purity and precision, with no mixing of fluids and a small but specific quantity. For example, Toyota orders the use of a dedicated Toyota Supercharger Oil poured into the gear transmission cavity. The oil level is checked with a dipstick, and the drain plug is used during service. The typical filling capacity is about 130 ml.
Power steering
The power steering system commonly uses ATF as a standard fluid. Older vehicles often lose fluid through leaks. To prevent pump damage from running dry during extended drives, it is advisable to maintain the fluid at the appropriate level using the recommended ATF, following manufacturer guidance.
Windshield Washer Fluids
Washer fluids may be formulated with diverse alcohol bases such as ethyl, methyl or isopropyl. They can be mixed with each other and with water, though care should be taken to maintain effective freezing and cleaning properties.
- If a strange puddle under the car appears, there are more than 11 possible causes and solutions worth reviewing.
- Information for drivers can also be found in Telegram updates under the same topic.