Last month General Motors shook up the North American automatic transmission ?uid market with its announcement of Dexron-VI. As Tim Sullivan reported in Lube Report April 13, GM intends to make Dexron-VI the ?uid of choice for all its cars and light trucks, starting with the 2006 model year Hydra-Matic transmissions. The trademarked ?uid can be used in all older Hydra-Matics, too.

Developed in conjunction with Petro-Canada and Afton Chemical, the new ATF spec is a signi?cant advance beyond GMs Dexron-III speci?cation. It also creates new hurdles expected to drive up licensing costs for additive and oil companies, including a requirement for ?eet tests and insistence that new chemistries be compatible with any others that have gained approval.

Dexron-VI does require higher-performing base oils. Experience to date, Aftons John Sunne told me, is that it requires a Group II+ or higher. Of two products that meet the spec using Aftons chemistry, one uses all Group III base oils, the other uses a blend of Group II+ and Group III. While Afton currently has the only approved Dexron-VI additive chemistry, others are expected to gain approvals.

To encourage the switch to Dexron-VI, GM will cease issuing licenses for Dexron-III(H) at the end of this year, and all such licenses will expire by the end of 2006.

What then will happen to the majority of North American service-?ll ATFs that carry licenses for both Dexron-III and Fords Mercon? It does indeed look like were going to see more segmentation in the ATF market. Lets hope the fastest-growing segment doesnt turn out to be cheap, obsolete ?uids.

If youre just learning about this now, you may need a subscription to Lube Report, our free weekly e-mail newsletter and North American base oil price report. See the current issue and subscribe at www.LubeReport.com.