Since the 1980s, the relentless pace of technical change to the automotive industry has had no better example than the evolution of automotive lubrication. The availability of new additive and base oil technologies over the last 25 years has influenced change in how lubricants are researched, fabricated, marketed, and, in the end, specified by OEM engineers as suitable for use in today’s engines and transmissions.
Industry and government collaboration have shaped the rules and regulations in which certain applications (such as motor oils) are created in regard to a lubricant with universal requirements and, more specifically, its formulation and manufacture to a national, or even world, standard for consumer and OEM protection.
Gear oils and greases have also benefited from the universal need for standards that protect the end user, no matter where they are.
But there’s always been one category of automotive lubricant that’s avoided regulation or control; one that’s evolved into an exclusive category of lubricants. These lubricants are designed and specified by the individual OEM, requiring exclusive use of that product: automatic transmission fluids.
The question I get most often is, “what happened?” In 1980, you could count the different types of ATF on one hand. What happened is a story of changing needs, technological advances, and different ways of engineering and viewing parts, fluids, and services, as the OEMs struggled to improve their bottom lines, while meeting engineering and political challenges over the last 35 years.
One of the most profound changes was the ability of lubricant blenders to take advantage of new technologies and base oils to solve problems at the same rate as other new technologies, such as computer-controlled transmissions and torque converters with clutches. In short, there was a gap in the rate at which these technologies could be used.
On top of that, the traditional notion of a vehicle warranty changed radically by Asian-based OEMs, who were anxious to grab their share of the North American market by offering extended warranties at double or triple what domestic OEMs were offering. With domestic OEMs now faced with the problem of competing warranties, the quality of “factory fill” and OE-branded, “dealer only” ATF became the next wave of change.
The automotive OEMs have been working since the 1970s to improve fuel mileage in any way possible. Since viscous drag is a significant contributor to energy inefficiency in transmission fluid, conventional wisdom says that reducing the viscosity of the transmission fluid would reduce fuel consumption.
For a long time, the OEMs benefited by using transmission fluids that were composed of a base oil with an additive package that allowed the fluid to shear down in viscosity quickly for better efficiency. These were the DEXRON II/MERCON and ATF+3 fluids of the 1970s and 1980s.
By the 1990s, things were changing rapidly with the arrival of computer-operated transmissions with electronic controls and extended warranties. Fluids that maintained stable viscosity and proved more durable for extended warranties became the driving force for change.
With OEMs now being driven by government regulations to improve fuel economy by any reasonable means possible, we’ve seen changing viscosity requirements for all lubricants used in modern vehicles.
Automatic transmission fluid in North America saw its first low viscosity ATF with the issue of the MERCON® SP specification in 2004. Prior to MERCON SP, the kinematic viscosity requirement for new GM and Ford ATF — and almost every other OEM ATF at the time — was 6.8 >cSt at 100ºC (212ºF) or higher, with most fluids falling in the 7.0–7.5 cSt range. There was no specified upper limit.
The MERCON SP was different because, for the first time, not only did the kinematic viscosity requirement drop from previous fluid types, but it was also given a lower and an upper limit (5.5–6.0 cSt at 100ºC). This was revolutionary, because GM and Ford had ATF specifications that were similar enough that dual GM/Ford fluid qualifications had become a standard practice for most oil companies. Not anymore.
Since the MERCON SP appeared, OEMs have shifted to using ATFs of lower viscosity. In fact, Ford now has a new ATF for 2017 models called MERCON ULV, and you only get one guess at what the ULV (4.5 cSt at 100ºC.) stands for: Ultra Low Viscosity. In 2005, GM went in that direction with the introduction of DEXRON VI ATF (6.4< cSt at 100ºC).
Since then, lower viscosity transmission fluids have become the preferred choice for the fuel-efficient generation of automatic transmissions, and we can expect to see more of the same with 8-, 9-, and 10-speed transmissions now coming into play.
And it doesn’t end there: Not only does the ATF sometimes have a color other than red — we now have amber, blue, and green ATF — the entry of new automatic transmission technologies that have different, unique fluid performance requirements further complicates the story. This has given rise to two more types of ATF you need to be aware of.
The first of these new fuel-efficient automatic transmissions was the CVT (continuously variable transmission), for today’s smaller, fuel-efficient passenger cars. They always reminded me of the big, variable-speed drill press in my high school shop class. It had two big, belt-driven, variable-size sheaves that would change at the same time, with one getting smaller and the other getting larger, to control spindle speed for drilling.
Of course, the automotive versions of these variable-output transmissions require a special ATF that’s unique to the application. Seems they need a traction fluid with specific frictional properties to work properly; shudder and wear are the issue. Now they’re standard on a range of vehicles and have evolved into their own thing.
The latest entry of automatic transmission options are the manual automatic transmissions: the DCT (dual-clutch transmission). Once again, the fluid technology required to make these dual-shaft, solenoid-shifted, manual transmissions work properly is in a category of its own. They come in dry- and wet-clutch versions and shift automatically if you choose that option.
Because they’re essentially manual transmissions shifted by computer- operated, mechatronic hydraulic circuits, the fluid has to be suitable for hydraulic actuators, robust enough to survive the hard duty cycle of a manual transmission, and have wet clutch frictional properties for the wet clutches some units have: another type of ATF now required for servicing these transmissions.
On top of that, dry clutch DCTs use straight-viscosity and multi-viscosity GL-4 gear oils (MTF): a big departure from the ATFs of the past and another source of confusion and inventory problems for shops and service providers.
In the last 35 years, we’ve gone from basically three automatic transmission fluids that were similar, to over three hundred OEM-specified and supplied ATFs that cover three different types of automatic transmission technologies. Is it any wonder technicians are asking, “What happened?”
In the past, we all liked to think the Magnuson-Moss Warranty Improvement Act would save us, because OEMs can’t void a warranty for not using their branded ATF. It can, if you’re able to prove the ATF you used is a suitable substitute for the required ATF.
Using a fluid that isn’t the right viscosity or type will immediately justify the OE dealers’ warranty denial, and you’ll be buying a transmission! Just ask the engine oil guys about OEM warranty denial for using the wrong viscosity grade or type of diesel engine oil.
The problem falls to how much we really understand when it comes to modern automatic transmission fluids. Can we justify our service fluid selections if we understand what they are and make our service fluid decisions based on knowledge of what’s required? You bet, but it takes education and access to information and training.
Opportunities in vehicle service today — especially if you service or repair automatic transmissions — are the result of training and attention to detail. With OEMs driving the market, the future of the aftermarket will depend on your ability to provide technical expertise combined with cost-effective service solutions.
