Mixing type F with other fluid?

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First post here. Been lurking for a long time. I've heard from a few people that you can mix a quart or two of "type F" to trannys that call for Dex II/III or Mercon to firm up the shifts. I could see how this would work because type F allows less slippage. Has anyone heard of this or tried it? Could this cause any harm? I'm thinking of trying this in my 93 Rodeo with a GM 4L30e (calls for Dex II) and my 91 Explorer with a A4LD (calls for Merc). I wouldn't think that these trannys would be too picky about fluid. So, bad idea??
 
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It works well on the old-school stuff (727, etc), but I wouldn't do it on anything computer-controlled.
 
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yes, some people have done it - but I would not. especially in an electronic tranny, as the algorythems are set for specific friction properties.
 
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I've always "fine tuned" the shift quality on my GN with a few quarts of Type F in the 200-4r.
 

MolaKule

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I would not recommend it in a modern CC unit unless you're going to race it, but then you will reduce the tranny's lifetime.
 
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Like mentioned by zrxkawboy, using type F will help shifts. This in an old trick used at the track for better ETs. But only for conventional trannys. The modern computer controlled stuff may not like it - it probably won't.
 
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Some rebuilders only used Type F. It produced the firmer shifts. On a 70's something car, it already had to be in advanced mileage. If the car was still on the road in 50k it would be unusual. TrickShift was a super saturated friction material ATF when it first came out. It did exactly as described ..for about 7k-10k when the "would be" racer pulled his pan to figure out why his trans wasn't working right ..and found loads of metal. They quickly evolved it to a milder product seeing that many of their customers (and the revenues that they generated) weren't from the exclusive drag racing crowd. I'd rather use a shift kit to rid myself of the cursed "velvety smooth shifts" (let me get a hold of the clown that never did that survey and asserted it as a tenet in autotrans design ) ..but, if you know what you're doing, and accept the potential liabilities ..
 

slinky

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Thanks for all the info! I think a shift kit is the way to go (I actually had the Transgo kit on the way already). I'm not really looking for racing performance . I was given the impression that less slippage= longer life .
 
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Also, some guys use B+M's Trick Shift [basically type F ATF]for manual transaxles to allow better shifting with synchronizers than regular ATF.
 
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 Originally Posted By: slinky
Thanks for all the info! I was given the impression that less slippage= longer life .
Generally speaking, yes. For softer shift you need co-applications in the transitions. The more shifting you do ..the more wear. If you shorten those common applied states, you get less wear. It was always interesting riding in a 60's something Euro (like an Audi LS100) and having the trans just "snap" into gear. I always though it harsh ..but more sensible than slowly wearing your trans away. I often thought that the action would move the fatigue points to outside the trans (motor/trans mounts - universals, etc).
 
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