The 411 on ATF: What You Need to Know About Automatic Transmission Fluid

The experts at Valvoline help us unpack the role automatic transmission fluid plays in your vehicle’s performance – and why it’s so important to pick the right one. 

Every day, our cars get a little smarter. They brake for unseen pedestrians, correct loose steering on the highway, and even take over the dreaded task of parallel parking on a crowded side street. But perhaps one of the greatest tasks the modern vehicle assumes responsibility for is the same one many automotive enthusiasts feel is most integral to the driving experience: shifting.

Modern Designs Make New Demands

The automatic transmission is nothing new, but the technology has certainly grown in popularity over the years – and complexity. While the four-speed slushbox hung around the American market until 2020, many modern vehicles now sport seven-, eight-, nine-, and even 10-speed automatic transmissions.

Those additional gears (and additional steps between gear ratios) provide the transmission with more flexibility as it constantly works to optimize itself, shifting to find the right gear that will keep the engine running most efficiently. (Think of how the versatility of your cooking improves when you have multiple spices in the cabinet – not just salt and pepper to choose from.)

The resulting bump in fuel economy comes at a cost, though. All that extra shifting means more moving parts, which means more opportunities for friction and wear – hence the need for intelligently-formulated lubrication, says Michael Warholic, Ph.D., Technology Manager at Valvoline.

“A transmission is a much more benign environment than an engine, but it still gets hot and there still is wear – metal buildup, degradation, chemical decomposition,” he explains. “The transmission oil does wear out; it just takes longer, which is why we often forget about it.”

Interestingly, a growing number of modern vehicles do not specify transmission-fluid change intervals in their owner’s manuals. Some don’t even have dipsticks or access plugs in order to check the fluid! In fact, many vehicles advertise a “filled-for-life” transmission – despite the average powertrain warranty only lasting around 5 years/60,000 miles.

Considering the average age of a car on U.S. roads rose to 12.1 years in 2021, it’s worth asking: When was your automatic transmission fluid (ATF) last changed?

Automatic Transmission Fluid Is Key to Overall Performance

“All the parts in the transmission are lubricated by one oil – the transmission oil,” Warholic says. “And that oil has probably 10 different functions, but the top two are (1) it has to lubricate the gears that are moving during shifting and (2) it provides the necessary friction to ensure the clutch packs remain 100% engaged.”

A clutch is basically a series of discs that are held together by the fluid to engage the gear. And much like a bad back, if those discs slip, your transmission is going to shudder in pain. That shudder not only can lead to poor drivability, but also a total failure.

Since the fluid brings friction, it’s critical to select one with the right balance of friction modifiers for your particular transmission. Otherwise, the transmission will slip or stick. “That’s one of the big differences between different fluids and designs – the type of friction you need,” Warholic explains.

For example, some OEMs – like Nissan, Honda, Subaru, and Toyota – have adopted continuously variable transmissions (CVT) in their vehicle lineups. A CVT does not use gears like a traditional automatic transmission. Rather, it uses two pulleys connected by a belt. The simple setup provides an infinite number of gear ratios, translating to better fuel efficiency and, in some cases, a smoother driving experience. The design also has very different lubrication needs, because of the difference in friction.

“Really, the only friction holding the belt to the pulley in this situation is the metal-to-metal friction and the fluid layer in between,” Warholic says. “So, if you don’t get the right fluid, it will slip. You never want to use a CVT fluid in an ATF application (or vice versa), or you’ll get very poor performance – and possibly do irreversible damage to the transmission.”

ATF Has Evolved

As transmissions grow more sophisticated, so do their fluids. Take the aforementioned 10-speed automatic. That transmission has a lot more gears and clutches in a very small package. To effectively lubricate all those delicate parts and still transmit power effectively, a thinner more free-flowing fluid is needed.

“The challenge with thinner fluids, however, is that the metal parts get closer together and so you have a higher propensity for wear,” Warholic says. “Therefore, the oil must be fortified with more or different anti-wear additives to protect the metal surfaces from wearing too quickly.”

Thinner oil also foams easier, which can affect lubrication. As a result, automatic transmission fluid has special anti-foaming additives to prevent aeration. On the bright side, these lower viscosity oils help with fuel efficiency, as a thicker oil would require more energy to pump around the transmission, as well as generate more heat.

Modern ATF formulations also include features like high-performance seal conditioners to prevent leaks and advanced additives to ensure reliable performance during fluctuating temperatures.

Make the Right Choice

With so many different transmission designs utilizing new materials and construction methods, the different types of ATF available have expanded as well. Generally speaking, the most common types are those designed and licensed by the largest domestic automakers. Dexron VI (GM), Mercon V (Ford), and ATF+4 (Chrysler) are formally approved by the OEMs for use in some of the most common transmission technologies. Some of these fluids can also be used in imported vehicles.

Warholic says higher-speed transmissions require newer componentry or technology in their formulations. The 10-speeds use a ULV or ultra-low viscosity fluid, while many eight- and nine-speed automatic transmissions are covered by the OEM-approved transmission fluids or by “multi-vehicle” fluids. Designed to work in a broad array of different transmissions, the multi-vehicle fluids are specially formulated and balanced with additives. However, CVTs still require their own special blend, so DIYers should be careful to select a CVT fluid formulated for their specific transmission.

To ensure your transmission gets exactly what it needs, you should always consult the vehicle’s owner’s manual.

Why Choose Valvoline?

Coverage. Valvoline’s automatic transmission fluid offerings include all the types listed above – plus special formulations for dual clutch automatics, older automatics, imported vehicles, and heavy-duty applications. “Valvoline’s ATF portfolio covers over 99% of the ATF specifications and applications that are out there,” Warholic says. “So, it’s very probable that Valvoline will have a product to suit your transmission.”

Innovation. Valvoline doesn’t just have broad coverage; it also has the latest coverage. “We’re constantly innovating to make oils that meet new transmissions,” Warholic says, noting the specifically-engineered ULV the company launched last year for Ford and GM 10-speeds.

“We also just reformulated our MaxLife Multi-Vehicle ATF to not only offer improved wear, foaming, and friction performance, but also to cover both step-gear transmissions and CVTs,” he says. “That was probably the biggest innovation. We’ve developed a balanced product which can cover our broadest ever selection of transmissions that are out there.”

Testing. Perhaps most importantly, Valvoline backs up its claims with both in-lab testing and on-road field trials. “We’re really putting the oil through its paces to make sure it works,” Warholic says. He points to a taxi fleet zipping around sweltering-hot Las Vegas and a trucking company of F-150s tackling the mountainous topography and harsh winters of Idaho. Such real-world situations really push a fluid to its maximum, he says, and provide helpful long-term observations.

For accelerated results, Valvoline turns to its dedicated full-scale engine lab – the only motor oil brand who can do so. There, highly skilled technicians put Valvoline products through extensive bench testing and chassis dynamometer trials to measure wear, friction, fuel economy, and more. The company also partners with its additive supplier, who do additional lab and field testing of their own.

Keep It Simple

Many car owners are comfortable handling their own oil changes, but even experienced DIYers know there’s value in having a professional change their transmission fluid and filter. Modern vehicle designs can make checking fluid levels or accessing the transmission fill point difficult. Those with sealed systems will require special tools or equipment to properly change the fluid. In addition to having these items on hand, a professional technician can check for leaks and inspect other key components like the pan gasket and transmission pan.

If you’re interested in seeing the difference Valvoline can make in your vehicle, ask your regular mechanic to make the swap. Or, head over to one of Valvoline’s Instant Oil Change or Express Care Centers. Certified techs can perform transmission fluid replacement services in as little as 20 minutes – saving you between 30% to 50% in costs versus the dealership.

What’s Next?

Valvoline is always developing new fluids. Currently, the company is working on an extended protection transmission fluid that will bring even more performance to the table. The premier synthetic product aims to deliver exceptional efficiency and durability, ensuring drivers get a smooth-operating transmission that will last longer than even the OEMs thought possible.

If you thought 155 years of tinkering with internal combustion engines would leave Valvoline unprepared for the EV revolution, think again. The company is actively developing special fluids to suit the very particular, specific requirements demanded by electric vehicles.

Most EVs have a single-speed gearbox regulating the electric motor, rather than a straightforward transmission. Fluid is still necessary for lubrication and anti-wear, as well as compatibility with electronics. Since copper is used in electric motors, and the motor is submerged in oil, it’s very important the oil does not interact with the copper and cause corrosion, Warholic explains.

“You also have to consider electrical properties. You don’t want the fluid to have high conductivity, so that the electrical charge dissipates from the motor – so it has to insulate too,” he says. “Plus, OEMs need every tenth-of-a-percentage of range extension they can get. So, the fluid is helping with that too by optimizing viscosity and lowering friction.”

Interested in learning more about Valvoline’s innovative products? Stay up-to-date on new offerings, including those in the automatic transmission fluid portfolio, by heading to https://www.valvoline.com/