The 20 and 80 refer to the temperature in Celcius.

You're supposed to be at the 20 mark when the fluid is at 20C or at the 80 mark at 80C. At the dealer they apparently can plug directly into a sensor to tell them the precise temperature of the fluid but after 20-30 minutes of driving you should be at 80C and the level should be at that mark.

You should have used the proper MB fluid which is synthetic (I think) although the bottle does not specifically say that, it just reads ATF fluid. They do have a new fluid for the new trannys which is supposed to be backward compatible that is also synthetic.

You should not be using conventional Dexron III in these 722.6XX transmissions under any circumstances.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz