Redline D4 vs. M1 Synth ATF in VW-ZF Tiptronic

[rusty]

I just finished a fabulously successful 51,000 mile run of Redline D4 in my 1998 Passat, whose ZF-Tiptronic tranny specs the Esso LT71141 fluid. In short, the D4 vastly improved shifting and lazy Torque Converter lockup, and when drained after 51,000 miles of hard driving (including track events and an unhealthy amount of TC loading at the dragstrip), still had some pinkish cast left, and didn't stink. Please forgive me for not doing UOA on it. (I still have the drained fluid - is it too late?)

You can read the long-winded details here, if you like:
Redline D4 ATF in my Tranny - 51,000 miles
Redline D4 vs. Tip Chip - D4 wins?

Two weeks ago, I changed the fluid to M1 Synth ATF. It was pure economics, plus a bit of experimental curiousity.

After 2 weeks and 900 miles, I have some definite changes to report regarding D4 vs. M1.

Caveat:
Redline D4 = 6 qts D4 plus 3 qts factory fluid
M1 = full 9 qts M1.

The M1 appears to have less slippery frictional additives than the D4. Supporting evidence:

(1) Lazy Torque Converter lockup in 2nd gear is gone. Just plain complete gone. The D4 got rid of 70%-80%, but the M1 has just eliminated it completely.

(2) Shifts are much firmer now - could be described as jerky. It feels like the clutches release faster and grab faster. The shifts themselves happen in the same amount of time, but the clutch engagement/disengagment is happening faster. The practical effect of this is that it is harder, trickier to throttle-match downshifts, and the revs jump up a little more between upshifts. Here's an illustration:

code:

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D4: /-----\

M1: |-----|

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(3) With the D4, if you downshifted without throttle-matching, it would of course give you a giant heave, but the engagement was always smooth. I never, ever had a shudder. This was over a year and 51,000 miles. Not one shudder. Downshifting w/o throttle matching, or even a badly botched throttle match, it never shuddered once. Whereas, with M1, just in the past two weeks, I've had three downshift shudders. Two from no matching, and one from a badly-matched one.

Number 1 I like very much.

Number 2 I'm ambivalent about.
Number 3 is making me think about changing back to D4.

I would appreciate some informed feedback on these observations.

 

[JHZR2]

this is OT, but how do you throttle match during downshifting in a tiptronic. Its still an AT without a clutch. I assume this 'throttle match' is similar to double clutching when downshifting an MT.

Just curious.

JMH

 

[rusty]

During the downshift, the engine will rev because the TC is a fluid coupling and its lockup mechanisms are disengaged. So you just artfully stab the throttle so that when the downshift completes, the engine revs match the drivetrain revs.

There are people who have told me flat-out that it is impossible to do this. They must live in a different universe, because I've been doing this since I was sixteen, starting with my '66 Mustang.

You can throttle-match on an MT without double-clutching. The extra "clutch" during a double-clutch is to match the synchro speeds.

 

[The Critic]

Redline D4 ATF is approved by Redline for all Esso LT71141 ATF specs, as I was told by Dave Granquist.

Pennzoil/Quaker State Multi-Vehicle ATF is also a suitable replacement.

I'm not surprised if M1 ATF does well since Redline D4 ATF is simply a std. Dexron III/Mercon fluid.

Michael

 

[unDummy]

D4 isn't a std DexronIII fluid. It is approved as a MerconV replacement which means its more HFM'd then DexronIII.

Because of the tip chip, or software shift kit, you are probably safe with dexronIII.
But, without knowing the details of the stock shift timings vs. the tip chip, I'd worry a little.

Do this comparison with pencil/paper/eraser:
Write something and erase it softly/gently. It might take several passes with the eraser but you don't wear out the eraser quickly. Write the same again and try to erase it in one aggressive pass.
Now, think about the clutch/band friction materials

 

[rusty]

quote:

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Originally posted by unDummy:
...Do this comparison with pencil/paper/eraser:
Write something and erase it softly/gently. It might take several passes with the eraser but you don't wear out the eraser quickly. Write the same again and try to erase it in one aggressive pass.
Now, think about the clutch/band friction materials

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That was exactly my concern.

OTOH, a friend who tried the M1 in the same tranny said that he noticed the same #2 and #3 behavior and his fluid was low. So I need to check the fluid before I do anything else. Up on the jackstands again - argh.