Since the 1980’s the relentless pace of technical change has no better example of how it has affected the automotive industry than the evolution of automotive lubrication. The availability of new additive & base oil technologies in the last 25 years has influenced the change in how lubricants are researched, fabricated, marketed, and in the end – specified, by OEM engineers as suitable for use in engines and transmissions they design and manufacture. Industry and governmental collaboration have shaped the rules and regulations in which certain applications (such as motor oil) are created in regards to a lubricant with universal requirements and more specifically it’s formulation & manufacturing to a national or even “World” standard for consumer and OEM protection. Gear oils and greases also benefited from the universal need to have standards that protect the end user no matter where they are. There has always been one category of automotive lubricants that has avoided regulation or control, that has evolved into a category of exclusive lubricants designed and specified by the individual OEM, requiring exclusive use of that product only. If by now you have not figured out what I am referring to then you do not work on automatic transmissions or use automatic transmission fluid.
The question I get most often is “what happened?” –
Well, in 1980 you could count the different types of ATF on one hand. The answer is one of changing needs, technological advances, and a different way of engineering and viewing parts, fluids, and service as the struggling OEM’s path to improved bottom lines met engineering & 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 & base oils to solve problems at the same rate as other new technologies (like computer controlled transmissions and torque convertors with clutches). In short, there was a gap in the rate at which these technologies could be utilized. On top of this, the traditional notion of a vehicle warranty was being radically changed by Asian based OEM’s who were anxious to grab their share of the North American market by offering extended warranties at double or triple what domestic OEM’s were offering. With domestic OEM’s 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 OEM’s have been working since the 1970’s 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 OEM’s benefited by using transmission fluids that were composed of a base oil with an additive package that allowed the fluid to quickly shear down in viscosity for better efficiency. These were the DEXRON II/MERCON and ATF+3 of the 1970’s and the 1980’s. By the 1990’s things were changing rapidly with the arrival of computer operated transmissions with electronic controls and extended warranties. Fluids that maintained stable in viscosity and proved more durable for extended warranties became the driving force for change. With OEM’s now being driven by government regulations to improve fuel economy by any reasonable means possible, we have seen this cause 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/Ford ATF (and almost every other OEM ATF at the time) was 6.8 >cSt at 100° C (212° F) 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 given a lower and an upper limit (5.5-6.0 cSt at 100°C). This was revolutionary at the time 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, OEM’s have shifted to using ATF’s 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 100 deg. C.) stands for (Ultra Low Viscosity). In 2005 GM went in that direction with the introduction of DEXRON VI ATF (6.4< cSt at 100°C). Since then, lower viscosity transmission fluids have become the preferred choice for the “fuel efficient” generation of automatic transmissions developed by OEM’s and we will see more of the same with 8,9 and 10-speed transmissions now coming into play.
It does not end here. Not only is the ATF colored other than red sometimes, (we now have amber, blue and green ATF) the story gets further complicated by the entry of new, “automatic” transmission technologies, that have different fluid performance requirements which make them unique. This has given rise to two more types of ATF the service provider/consumer has to be aware of.
The first one of these new “fuel efficient” automatic transmissions were the CVT (continuously variable transmission) units for smaller fuel efficient passenger cars of the day. 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 is unique to the application. Seems they need a “traction fluid” with a specific frictional properties to work properly (shudder and wear are the issue). Now they come standard on a range of vehicles and have evolved into their own thing.
The latest entry into the 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 are automatically shifted if that option is chosen. Because they are essentially manual transmissions shifted by computer operated mechatronic hydraulic circuits, the fluid required 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. Again, another type of ATF now required for servicing these types of transmissions. On top of that dry clutch DCT’s use straight viscosity and multi viscosity GL-4 gear oils (MTF), a big departure from the ATF’s of the past and another source of confusion and inventory problems for shops and service providers.
In the last 35 years we have gone from what was basically three automatic transmission fluids (that were similar) to over three hundred OEM specified and supplied ATF’s that cover three different types of automatic transmission technologies. Is it any wonder technicians are always asking “what happened?”!
In the past, we all liked to think the Magnuson-Moss Warranty Improvement Act would save us, because OEM’s can’t void a warranty for not using their branded ATF. It can, if you are able to provide proof you have used a suitable substitute for the required ATF. Using a fluid that is not the right viscosity or type (ask the engine oil guys about OEM warranty denial for using the wrong viscosity grade or type of diesel engine oil) will immediately justify the OE dealers warranty denial actions and you will be buying a transmission! 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 is required? You bet, but it takes education and access to information & training that makes this happen. Opportunities in vehicle service today (especially if you service or repair automatic transmissions) are the end result of training and attention to detail. With OEM’s driving the market, the future of the aftermarket will be determined by the ability of the service provider to provide technical expertise combined with cost effective service solutions.