There are a lot of details to absorb, and for that Ive done what many lubricant blenders and marketers do: turned to some good folks at the major additive suppliers for their input.

One of the first things I learned was that automatic transmissions (or at least their ancestors) have been around for a long time. For instance, in the year 1490 Leonardo da Vinci drew a sketch describing what many believe represents how a continuously variable transmission (CVT) would work. Wow!

By 1904, automobile manufacturers were hard at work developing mechanisms that would shift automatically to give the best performance at any combination of engine and vehicle speed. The first devices were completely mechanical, involving fly-weights, bands and clutches to select the desired gear. While these were improvements over non-synchronized manual transmissions, they did require the drivers skill in knowing when to shift and how to make a smooth start. In addition, metallurgy was not up to some of the demands placed on these early transmissions, so mechanical failures were not uncommon.

The real start of automatics came in 1934 when Reo and General Motors first developed semi-automatic transmissions, utilizing planetary gear sets and hydraulic couplings. They still required a clutch but were easier to operate. Meanwhile, Chrysler also was working on fluid couplings for automotive use. While Chrysler didnt adopt them in their own transmissions, the combination of all three features (planetary gears, hydraulic couplings and fluid clutches) was incorporated in the GM Hydra-Matic transmission. Introduced in 1939, it dominated the automatic transmission market for the next 25 years, with periodic improvements. Two of these improvements were the introduction of a second fluid coupling to smooth out the shift, and the addition of the park setting with its locking pawl feature.

The next big improvement was the torque converter which was introduced as the Buick Dynaflow in 1948. A torque converter differs from a fluid coupling in that it provides variable torque multiplication at low engine speeds, while a fluid coupling does not. Both torque converters and fluid couplings prevent an engine from stalling at low speeds even when the transmission is engaged. Over the next two decades, further design refinements resulted in some very efficient and reliable transmissions.

In the mid-1990s, the on-board computer became an integral part of powertrains, with impact on transmission design and operation. The computer, in addition to controlling emissions and ignition, was able to fine-tune the selection of the proper gear setting and adjust engine speed for the most efficient and smooth transition from one speed to another.

Today, transmissions are undergoing further change to maximize fuel economy, shift feel and durability benefits. The current North American automobile fleet is predominantly five- and six-speed step transmissions, but new concepts such as the double or dual clutch transmission (DCT) and the continuously variable transmission (CVT) are beginning to take their place in vehicle power-trains. In fact, its estimated that the dual clutch transmission will become as much as 10 percent of the market in the next 10 years. (See related story, page 16.)

Initially, DCTs are expected to displace the manual transmissions that are most popular in Europe, but they could make their way into many other applications and regions. They shift rapidly and without as much loss in economy as conventional automatics.

CVT transmissions are primarily found today in Asia and are mostly in vehicles with 2-liter and smaller engines. The only exception to that rule is the Nissan product line, including the crossover Murano.

Naturally, ATF formulations have changed through the years as well. Originally, transmission fluids were simply engine oils or gear oils. As the transmission developed and its unique lubricant requirements surfaced, oil formulators began to develop additive components and to select appropriate base oil fractions to enhance the properties they required.

Nowadays, ATF is about as complex a mix of additive componentry and select base stocks as you can imagine. The components are often found in other additive packages, such as for engine oil formulations, but the combinations and treat rates are unique to ATF.

A list of the ingredients for ATF is as follows:

Base stock, crucial to ATF performance.

Dispersants, needed for sludge and varnish control.

Antioxidants are used to protect against oxidation.

Antiwear agents protect moving parts such as planetary gear sets and bushings.

Friction modifiers provide proper clutch plate and band frictional properties.

Corrosion inhibitors protect metal surfaces from rust and corrosion.

Seal swell agents keep the system tight, to prevent leakage.

Viscosity index improvers allow for suitable viscometrics over a wide operating temperature range.

Pour point depressants (PPD) enhance low-temperature fluidity.

Foam inhibitors control the formation of foam – bubbles dont lubricate very well!

Red dye is used to identify ATF.

As we used to say, thats a real dogs breakfast! Where are North American automatic transmissions and fluids headed? ATF experts in the additive industry tell us that on the transmission side, six-, seven- and even eight-speed step transmissions are the latest design innovations in the clutch pack, planetary gear designs. These transmissions allow for good fuel economy and the kind of smooth operation that the driving public expects.

There also are new and not so new designs on the horizon which promise to be even more efficient. One that has been around for a few years is the CVT, which makes use of metal chains and belts to continuously match engine speed and load to driving conditions. This allows for almost seamless shifting and exceptional fuel economy, especially for smaller engines. The drawback, so far, has been difficulty in scaling up the design for heavier vehicles like the SUVs and light trucks that are so popular with U.S. Drivers.

Another relative newcomer, the DCT, is a clever design which some believe approaches manual transmission efficiencies. It uses a pair of clutch and shaft assemblies to provide nearly instantaneous shifts from one gear to another. There is no hesitation as gears change, and it is one of the more fuel-efficient designs just now coming into production.

From the perspective of the fluids, the big push is to lighter-viscosity oils for better fuel economy. That means higher-quality base stocks will be required. API Group II and III base stocks already are being used in many products meeting current ATF specifications for step transmissions, such as Chrysler ATF+4, General Motors Dexron VI and Fords Mercon V fluids. Currently, many transmission warranties run for 100,000 miles, so its not out of the question that even longer warranties will make their appearance soon. The use of Group III will continue to grow, predict my additive company sources, and Group IV base stocks (polyalphaolefins) could increasingly find their way into ATF as fill-for-life applications grow.

In addition to base stock improvements, V.I. improvers are being upgraded. More shear-stable polymers are being used and some of them are multifunctional to aid in keeping the transmissions moving parts cleaner. Friction modifiers are being improved to achieve gains in shifting performance.

One concern is that simply reducing ATF viscosity (currently at 5.3 to 5.9 cSt at 100C in some transmission fluid specifications) to as low as 4.5 cSt at 100C could well result in more wear problems. That means that antiwear components will need to be improved as well, to protect gear sets. At lower viscosities, there is even concern about air entrainment and foaming which can result in internal leakage and loss of performance.

Certainly the introduction of more additive componentry will mean more possibility of oxidation problems, so that chemistry will be beefed up as well. All in all, a more robust ATF is on the horizon. This certainly increases the resources and investment required by additive companies to develop those new components as well as to meet the complexity of todays base oil availability and demand.

Add in the similar needs for investing in CVT and DCT lubricant requirements, and the specialized testing and development work they require, and its easy to see how additive companies have their hands full providing lube marketers and OEMs with enabling technologies.

On the marketing side, as many of you are aware, there are a number of current OEM specified ATF products. GM, Ford, BMW, Honda, Volkswagen, Nissan, Toyota and Hyundai all maintain their own specifications. However, there are a large number of vehicles on the road which are out of warranty. Many of these are old enough that Dexron III and/or Mercon were the only recommended fluids. Dexron III and Mercon were licensed for many years by GM and Ford, respectively, but they now are obsolete, replaced for service fill by Dexron VI and Mercon V. All Dexron III licenses expired as of Dec. 31, 2006, and the Mercons followed suit six months later. Officially, these fluids dont exist – but the vehicles do. Average vehicle age in the U.S. fleet is more than nine years.

So how does the marketplace deal with the problem of multiple fluid specifications and large numbers of vehicles that dont require the latest product? What appears to be happening is that a two-tier market is developing for ATF.

For those vehicles still under warranty, the OEM-specified product is used. At most quick lubes, it isnt practical to carry all of the specified fluids so the store operators will have to make some judgments based on the vehicle mix they serve. For repair shops, its possible to call their lube distributor for the proper product and get it, usually within half a day. New-car dealers will obviously carry their OEMs current product.

For the unwarrantied masses, there are some new products called multi-vehicle fluids. These claim to embody many of the properties of the older ATF requirements, and can be formulated to meet Dexron III, Mercon and some of the foreign-car requirements. Thus, they may satisfy the older vehicles on the road such as my 2001 GMC pick-up. However, they cannot secure the required product approvals and licenses which OEMs demanded in the past, so there is no over-sight on product quality.

At any rate, these products appear to have strong appeal for quick lubes seeking a nearly universal fluid to offer the majority of their customers. They also find their way into some of the repair shops, since older transmissions are the ones most likely to show up needing significant work. Its doubtful that new-car dealers will need to carry a product like this, since the new Dexron VI, ATF+4 and Mercon V specs are backward compatible, and can be used to service older models.

Despite this swirl of specifications and confusing market, the future is bright for ATF. As older vehicles are phased out and newer ones take their place (with or without government help), the requirements for ATF will become more demanding and specialized. On the world scene, as more vehicles move from manual to automatic transmissions, the market for ATF will grow.

It probably never crossed Leonardos mind that his idea for a transmission would result in the market for fluids and mechanisms that we now see. Wonder what he would say if he could see it all now?

Bravo, bravo!