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Brian Wagner May 09, 2018The transmission in your racecar takes a considerable beating between the raw horsepower you try to force through it and having immense pressure applied before the green light drops on each pass. Having a well-built unit will certainly help the transmission’s longevity, but a part of the equation that’s just as important is the fluid you’re using inside that transmission. We got the low-down on automatic transmission fluid (ATF) from Erik Brock at
HPL that covers what properties your fluid should have and how HPL’s line of ATF can help your car perform its best.On the surface, ATF is a distant cousin of engine oil; it lubricates the internal parts of an automatic transmission, and perhaps more importantly transfers power through the torque converter. The role of ATF is more than just that simple breakdown, it keeps the transmission cool while assisting in the process of transferring debris to the filter of the transmission, as well. So, ATF must maintain a balancing act between keeping certain parts cool and lubricated, while fighting unwanted wear, oxidation, and shearing—all while transferring what could potentially be thousands of horsepower through the torque converter.
The fluid you select will have a big impact on the car’s performance and how long the transmission will live between service intervals.
You can get ATF in formulas that use a petroleum oil base as well as a full synthetic blend. The formulation for each type can vary greatly and will change how the fluid behaves inside the transmission. If the mixture isn’t strong enough, it will lead to the clutches inside the transmission slipping at too high of a rate, robbing your car of performance while causing extra wear on transmission parts. The ATF you select needs to have the right formula that protects parts, while not causing the clutches inside the transmission to slip excessively.Every ATF fluid on the market has to meet the standards of the American Petroleum Institute (API) to receive one of their API ratings from GL-1 to GL-5. As the rating goes up it indicates that the fluid is rated to handle more pressure without the metal parts inside the transmission making contact. Besides the GL rating, ATF fluids also receive a Viscosity Index (VI) rating that indicates how the viscosity of the fluid changes at different temperature levels. A higher viscosity index rating means the fluid is less likely to be affected by big temperature changes.
What To Look For In Automatic Transmission Fluid Not all ATF is created equal, so shopping based on price for a high-performance application could lead you down the boulevard of parts failures and inconsistency. The ATF you select needs to be able to stand up to the punishment of the environment it will be placed in, so there are a few things to consider before you purchase and pour.