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FAST LUBE SECRETS
by Jack Zakarian

Automatic Transmission Fluid Performance Requirements On the Rise
There is a significant trend in the automatic transmission fluid (ATF) market now. Performance requirements have risen steadily the past few years to accommodate not only the automakers’ transmission design changes, but also their push for fluids to last longer and perform better.

One important example of this trend hit the market on April 1 this year. General Motors (GM) announced a new factory-fill ATF for all of its 2006 model-year cars and trucks equipped with Hydra-Matic transmissions. The new fluid will meet the Dexron-VI specification, which is a significant upgrade over the current Dexron-III spec.

This announcement caught many long-time industry observers by surprise. GM had only recently upgraded its Dexron-III spec from the “G” level to the “H” level. Now, all of a sudden, the H level will become obsolete by the end of 2006. Never before has the pace of ATF spec changes been so quick.

Many speculated that GM was developing a new generation of ATF specifically for its new six-speed, rear-wheel-drive transmissions, but the switch of GM’s entire factory-fill to a more expensive, higher performance fluid that was specially designed for six-speeds was unexpected. The factory-fill began in April with the new Hydra-Matic 6L80 transmission.

So, what does this mean for the oil change market? Most likely, this announcement is the straw that will break the back of a universal ATF. Most vehicles on U.S. highways today can get by with a standard Dexron-III/Mercon ATF. A lot of oil companies offer a multi-vehicle, or universal, ATF that will cover the standard Dexron-III and Mercon specs, as well as the Mercon V spec, and Chrysler ATF+3 and ATF+4.

However, the new GM spec will be impossible to combine with the Mercon requirements. The new GM ATF will specify a maximum viscosity of 6.4 cSt at 100º C, whereas the Ford Mercon and Mercon V specs call for a minimum viscosity of 6.8 cSt at 100º C. You can’t be less than 6.4 and greater than 6.8 at the same time!

It’s possible that future Ford specs may match GM more closely. Right now, Ford has a number of factory-fill ATFs: Mercon, Mercon V, Mercon SP and CVT fluid. It is working to simplify its system, and it may choose a lower viscosity ATF. Toyota has already gone lower with its new ATF, known as T-V, compared to its previous T-IV fluid.

The trend in ATF viscosity is to go as light as possible without sacrificing wear protection. One reason is that lower viscosity ATF is easier to pump in hydraulic circuits. However, the most important reason is that lower viscosity ATF will deliver better fuel economy - a key issue for OEMs trying to meet tight government fuel economy standards.

Another impact upon the installer market will be the price of the new ATF. Because of the more stringent ATF test specifications, the base oils and additives needed for Dexron-VI will be higher quality and higher cost than what is used in today’s Dexron-III fluids. In addition, there is only one additive supplier approved for Dexron-VI. The cost to run a GM qualification program could well be over a million dollars - a figure that will give pause to other additive suppliers who want to get official approval. Thus, with only one source of officially approved additive supply, you can almost certainly expect no price relief for the new GM fluid.

Why did GM insist on a new fluid? The company’s press release makes it clear that it is striving for superior transmission performance. That, in turn, should improve customer satisfaction and, most important for GM, cut down on warranty work. For example, the new Dexron-VI will have the following advantages compared to current Dexron-III:

More consistent viscosity during service(that is, very little sheardown).
More consistent shift performance, especially in extreme conditions.
More than double the durability in friction characteristics.
More fluid life by about 50 percent.
You can get one indication of the tighter spec limits by comparing the requirements that GM has placed on its cyclic shifting test. For the Dexron-III G spec, you had to achieve acceptable cycling test performance for 20,000 cycles. For Dexron-III H, the bar was raised to 32,000 cycles. And, for the new Dexron-VI, you have to perform well for 42,000 cycles.

Many other performance tests, such as ATF oxidation life, have similar increases in spec requirements. The GM oxidation life test is run in a 4L60 transmission operated continuously at 325º F. For the Dexron-III G spec, researchers run the test for 300 hours and the increase in oil acid number is limited to 3.25 or less. For Dexron-III H, researchers increase the test length to 450 hours, with the same limit on acid increase. With Dexron-VI, the test length is 450 hours, but the allowable acid number increase is 2.0 or less. This superior performance under high temperature conditions has allowed GM’s new ATF to be designed for drain intervals of 100,000 miles (normal service) or 50,000 miles (severe service).

Some have asked why GM didn’t call its new fluid Dexron-IV. A possible answer is that it wanted to reinforce the fact that the new ATF was specially made for six-speed transmissions. Another possibility is that GM wanted to leapfrog over Chrysler and Ford, whose latest generation fluids are known as ATF+4 and Mercon V, respectively.

For the time being, the ATF market will be stable. It will be at least a year before new GM vehicles will need ATF service. Also, the number of 2006 model-year vehicles on the road will be much smaller than the rest of the vehicle population.

It is not clear yet how many oil companies will be ready to supply Dexron-VI. They may take a wait-and-see attitude before rushing into production of a fluid with limited sales. The good news is that Dexron-VI will be backwards compatible for all previous GM transmissions that required Dexron-III or II. That means that you can install Dexron-VI in any GM transmission and it will work.

Dr. Jack Zakarian is a consulting engineer with 26 years of experience in the Lubrication Technology Group, Chevron Products Company. He is a product specialist responsible for automatic and manual transmission fluids, gear oils, drive train oils and tractor hydraulic fluids. To find out more about the products Zakarian develops or about Chevron’s PowerBuilder program, call 1-866-688-8890 or visit www.chevron.com.

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