Fifteen years ago, you could service most of the worlds automatic transmissions with just two or three fluids. Today you need dozens, as hardware types diverge and OEMs lay down the law on fluid performance. Is even more confusion ahead now, as NIST and the state of California are trying to nail the lid on obsolete and multi-vehicle ATF?
When you get into your vehicle and start it up, some amazing things happen. Fuel is burned and power is created. But that power has to be directed to the wheels to get you out of the garage and onto the road. Thats the role of a remarkable device: the transmission.
An automatic transmission employs a series of gears to smoothly transfer power from the engine to the driveshaft in order to rotate the wheels. By changing the gear ratios, the transmission controls torque variation, speed and direction, and enables the engine to operate at peak efficiency and optimum fuel consumption.
Variations include planetary automatics, automated-manual hybrids, continuously variable transmissions (CVT) and dual-clutch transmissions (DCT). This article focuses on automatic transmissions and their fluids, but outside the United States manual transmissions are still on the scene, and sell steadily in Europe and Asia-Pacific.
Depending on what part of the world your vehicle comes from, you may see one type of automatic preferred versus another; however, all types are used by most OEMs, so theyre generally available worldwide. Here are the leading types:
Planetary (stepped) transmissions date to the 1930s, and are the most common type in U.S. light-duty vehicles. They shift through a series of gear ratios, actuated by clutch packs and brake bands. Most include a torque converter to take power from the engine, and multiple planetary gear sets.
CVTs, by contrast, do not use traditional gears for change of ratio. Instead a belt or chain links two pulleys with variable diameters. (Think of a pair of opposing cones.) As these pulleys separate or move closer, the gear ratio is determined by the active radius of one pulley relative to the other. This means that a CVT effectively offers an infinite number of extremely close ratio gears. Offering smooth acceleration and almost zero shift-feel, these are the choice of many Asian automakers.
DCTs, which are popular in Europe, have become synonymous with high performance, fast and smooth shifts, and improved fuel economy. DCTs are essentially two manual-type step transmissions working in tandem. One gear shaft holds the even-numbered gears, and the other contains the odd-numbered gears. While youre accelerating in one gear, for example, a computer selects the subsequent gear on the opposite shaft. When its time to up-shift, the clutch that controls the even gears disengages and the clutch controlling the odd gears engages.
The issue today is how to successfully lubricate this collection of differing technologies as well as the existing car parc. Must each vehicle have an OEM-specific product? Or can they be handled by a one-size-fits-almost-all fluid?
This is not a new dilemma. The first modern ATFs were introduced by General Motors and Ford. GMs automatic transmission design was based on multiple clutch plates and was intended to provide a smooth shift. With greater clutch surface area, the GM products were able to generate the necessary torque with a fluid having a low coefficient of friction.
Fords design decisions evolved from Henry Ford himself. For cost reasons, he wanted to use the minimum number of clutch plates in the transmission. So to provide the needed torque, a very high coefficient of friction fluid was required. This caused a much harsher shift feel.
It wasnt too long before drag racers with GM transmissions were using Fords Type F fluid, wedding the formers larger surface area to the latters friction characteristics to ensure a more positive launch off the starting line.
As demands grew in the 1980s for fuel economy, reduced emissions and longer transmission life, hardware evolved into multi-gear and overdrive designs, with lasting impact on fluids. GM trademarked its Dexron fluid, and Ford abandoned Type F and trademarked its own Mercon fluid – which in many ways was identical to Dexron.
For a while, this meant that the composition of many ATFs could be handled fairly easily, especially since most transmissions were multi-gear automatics. But after 1995 the situation became more complex, and since 2005 it has become downright unwieldy.
In January, consultant and transmission fluid expert Jack Zakarian, formerly of Chevron, presented a review of the past and current situations at a meeting held by the National Institute of Standards & Technologies in San Diego, California. Prior to 1995, he noted, life was pretty simple. There was Dexron-II, used by GM and many foreign OEMs; there was Mercon; and there were multi-vehicle ATFs that could meet both, often labeled as Mercon/Dexron. There also was Chryslers ATF+3.
From 1996 to 2005, though, things got a bit more complex, Zakarian said. In addition to all of the older specifications, formulators had to consider upgrades like Ford Mercon V, Chrysler ATF+4 and multiple first-generation ATFs from foreign OEMs. About the same time, advanced hardware designs – six-speeds and more, CVTs, DCTs, hybrids – began to make big inroads, primarily from those foreign influences.
As Europeans embraced DCTs, Japanese makers were using CVTs and pursuing a system of Genuine Oils which are unique and proprietary to their vehicles. There are no specifications issued and only the OEMs oil is permitted for service. However, up until around 2005, the Japanese accepted oils that were identified in the Japan Automobile Standards Organizations list of transmission fluids approved for use-the only approved product substitution list known.
Further twists since 2005 have brought the market to the fragmented stage, Zakarian continued. GM adopted Dexron-VI and withdrew its earlier specs, Ford moved all its vehicles to Mercon V, Mercon SP or Mercon LV, and new generations of foreign-OEM ATFs entered the fray.
Today, Zakarian pointed out, the ATF landscape includes more than 30 fluid standards, many of which have no specification available to the public. These proprietary products are designed by the OEMs specifically for their transmissions.
The question looming now: How can a garage, quick lube or other service provider get the right fluid for the transmission being repaired? Of course, one answer is to go to the appropriate dealership and buy the fluid there. However, that has an impact on cost-dealer-sourced fluids are expensive-and on timing. For quick-lube customers, this can be a major inconvenience since going to the dealer to pick up the fluid negates the quick in quick lube. It may also influence the customers choice of where to have their vehicle serviced: If the transmission fluid has to come from the dealer, why not do all the maintenance there? Independent installers worry they could lose market share.
A third issue is whether or not a non-OEM fluid is a suitable product. Multipurpose fluids have been available for some time, the most famous being Dexron-III/Mercon or Dex/Merc products, as Zakarian pointed out. Ford and GM declared these specifications obsolete about 10 years ago, and the vehicles that originally needed them are long out of warranty. However, for older vehicles whose drivers dont want to switch to newer products, unlicensed fluids labeled Suitable for Use have been marketed for several years and may be serviceable replacements.
Enter the State of California. In 2015 California enacted Assembly Bill 808, which mandates the proper labeling of automotive products including transmission fluids. Allan Morrison, senior environment scientist at the Fuels and Lubricants Laboratory Division of Measurement Standards (under the states Division of Food and Agriculture), conducted a webinar in July in which he discussed the issue.
The most pressing and confusing part of the legislation, he explained, is the so-called Duty Type Classification. For labeling purposes, AB 808 defines duty-type classification in two parts. First, what type of transmission does the fluid cover? The naming must conform to industry recognized terminology such as Dual Clutch Transmission Fluid. Second, a product name or specification is required, and should reference the OEM product name or specification, a consensus organizations specification, or the producers product name or specification.
Historically, the OEM specification name and product license number (e.g. Dexron approval) were recognized as sufficient. With the introduction of new transmission types and the decision by many OEMs to not publish a specification or test limits, this approach is now in question.
Nor can many ATF products cite a consensus organization. JASO lists some fluid specifications which may allow some coverage, but North American organizations such as the American Petroleum Institute, SAE International and ASTM have not been active in ATF standards because the OEMs had their own approvals and licensing schemes.
The third option, in which an OEM may recommend an ATF by brand name, is cause for great concern, oil marketers report. If a competitors fluid is the recommended product, there really is no way anyone else can supply a product.
For many garages and quick lubes, ATF will be very difficult to offer unless they can get the proper fluid for the vehicle they are servicing. The Automotive Oil Change Association, the Independent Lubricant Manufacturers Association and API have been involved in addressing this situation.
One answer may be to revise NISTs Handbook 130, which covers Uniform Laws and Regulations in the Areas of Legal Metrology and Engine Fuel Quality. Handbook 130 sets industrywide standards for such things as labeling for lubricants, and is traditionally ahered to the oil industry as well as state regulators.
Kevin Ferrick, who manages engine oil programs at API, indicated that the group has proposed changes to Handbook 130 to address the labeling of transmission fluid. These are being considered by the four regions of the National Conference on Weights and Measures, which develops and writes technical standards nationwide. API hopes that its proposals will be moved to voting status in time for NCWMs annual meeting in July 2017.
Among APIs proposals is the following, intended to address the duty-type classification required under Californias AB 808:
The primary performance claim or claims met by the fluid or reference to where these claims may be viewed (for example, website reference). Performance claims include those set by original equipment manufacturers and standards-setting organizations such as SAE and are acknowledged by reference.
API also pitched the following for Handbook 130:
Transmission fluids that are intended for use only in certain transmissions shall meet the original equipment manufacturers requirements for those transmissions or have been demonstrated to be suitable for use in those transmissions. Adherence to the original equipment manufacturers recommended requirements shall be based on tests currently available to the lubricants industry and the state regulatory agency. Suitability for use shall be based upon appropriate field, bench and/or transmission rig testing. Any manufacturer of a transmission fluid making suitable-for-use claims shall provide, upon request by a duly authorized representative of the Director, documentation of such claims.
It is obvious that the next few years will be awkward with regard to ATF labeling and acceptability. No one has proposed any system like APIs Engine Oil Licensing and Certification System to bring order to the scene-and it is unlikely to be done, given the presence of more than 30 active transmission fluid types in the market.