Just had a customer tell me their converter company suggested TYPE F fluid for their 4L60E .
I wont mention the company but DO NOT DO THIS. The only way it would be acceptable would be if PWM pulsed width modulation was either mechanically or in tune eliminated .
Doing so without these can/ will result in serious converter chatter during lockup clutch apply and release and even under some driving conditions which trust me is a horrid feeling or vibration like feel in the car or truck .
Not to mention TYPE F has 0 advantages over DEXRON 6.
TYPE F IS FOR ANTIQUE FORDS with C6-C4- PRE- LOCKUP CONVERTER ERA TRANS .

 

I had seen somewhere where a converter company suggested Type F fluid for their lock up converter, but I can't remember who it was. I couldn't believe they didn't even know what fluid their converter required. There is no way on this earth I'm Type F fluid in any transmission, not even a Powerglide.

 

"NAME the Company"

 

fluilds
Na I dont play the name and shame game, They are not a sponsor here I will say that. Just was blown away.
Been here done that with someone using TYPE F in a PWM trans and it shuddered like hell during lockup engage and at low speed lockup when PCM allows it to slip ,
Solution was TRANS FLUSH and even then took DEX 6 AND 4 BOTTLES of LUBEGARD SHUDDER FIX Friction modifier to get it right . Was ok after that however.

Now way back in the day people did put TYPE F in th350s and 400s . It had a higher heat range and would give a little firmer shifts . But lockup units and such or like the 700r4 and 4l60e with overlaps on 2-3and 3-2 no way . Todays fluid's are so so much better in every possible way .

 

I worked one day in a transmission shop to try out, it think that was about 48 years ago, the fellow showing me the ropes put type F in a Turbo 350, and said that is all they use is type F, I was floored. Maybe I was being set up too, who knows. I never went back there.
I thought F was similar to what B&M fluid was, since it supposedly offered less friction reducing additives than Dexron. I'd only be adding any special different fluids if the parts were all new clean etc. I'd never be mixing them.

 

Yes back in the day using type F in GM TH350, 400. POWERGLIDES ETC WAS NORMAL in the performance realm and was fine as compared to early dexron it had less friction modifiers so "firmer shifts" and it had a higher heat range also good.
But with the coming of lockup converters this was problematic, In the early days it would just result in an abrupt grunt on apply. Annoying but livable. But then the 700r4 and the 2004r and overlapping 2-3 3-2 didn't work out well . Then the PWM converter clutch instead off on off and chatter chatter rumble.
Not that I think it will actually cause harm as such at least not in the shorter term. But it just makes no sense. Newer synthetic oils handle far more heat , last longer, protect seals better, lubricate parts better and have much more stable viscosity. They literally do everything better.

 

I agree with Frank; if we're talking 48 years ago and a TH350 trans, there was nothing wrong with using Type F. In fact, it would still be fine in a TH350 today (just like the old B&M "trick shift"... do they even still make that?) There are better options today, but you won't hurt a TH350 with Type F and it certainly wasn't a mistake to use this back in the '70s.