Originally Posted By: SPK2000
I was under the impression that a CVT was like snowmobile belt drive and assumed it did not need fluid. It certainly does not have the friction plates in a standard or normal automatic transmission. What is the fluid needed for?
Some CVT's are coupled to a Torque Converter (TC) and even Lock-Up TC's. So then a fluid is needed for it and to provide cooling, proper traction coefficients, and to prevent wear between the linking mechanism and the Variators.
Here is a post that may help that I made in the ATF, Differential, Trans, Brakes, P/S forum:
Quote:
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Step-Shift ATF's and Friction Modification
The question of coverage has also been raised with the Dexron/Merc (Step-Shift) type fluids. If the Dex/Merc "Multi-Vehicle" ATF fluid has the proper friction modifier chemistries to support support a range of dynamic friction coefficients Mu(v), then they can provide a range of coverage and specifications.
Belt/Chain CVT's rely on another type of friction or coefficient of friction and that is called the, "Traction Coefficient."
This "Traction Coefficient" has to be within a certain range of values in order to properly transmit power and not let "slippage" occur, so special friction modifiers are part of the chemistry. The rest of the fluid contains base oils, Anti-Wear additives, and other components.
Now if the CVT fluid has the proper friction modifier chemistries to support support this range of "Traction Coefficients" then one fluid can cover Nissan NS-1 through NS-3 and other specifications.
As mentioned in other threads on ATF, whether it be for Step-Shift's or CVT's, ATF's are the most additized fluid in the automotive drivetrain because of these specialized friction modifiers.