Many say a TF must use Type F and then one of the foremost TF guys, Rick Allison at A&A says ATF+4. Bottom line, it all works. Choose what you like best or think works best

If I make the switch to John deer hydraulic fluid, can I just pull the trans and drain it and drain the converter? or does it have to be a empty fresh rebuild trans and converter?

I basically agree with everyone. It seems many have used the type they like for years and have had good luck with it. Myself I use the Mopar ATF+4 but since I was a tech at a Dodge dealer for 24 years and did auto trans work along with the other work I did I have a small stock of the ATF+4 since we usually would charge out an extra qt of fluid on warranty jobs and us guys who did trans work always had some extra. So it is good on my pocket to use the ATF+4 and its worked great for me for many years. But I would have no problem using some of the others mentioned on here either. Ron

I also use ATF+4, it's what I was told to use by Tranzact so I listened.

The one reason I run the type F is the guys
in the trans lab at Chrysler... I had plenty
of friends in there and asked this question
when I started racing... ALL of them said F
so I did.. some of them were racers with quick
cars... and the first trans that I used was built
by one of those guys and again he said type F..
but this is my junk 727
EDIT
this is still a trans from the 60s so whats so
different...... JMO on this.. since I dont race
big dollar stuff

Drain it, change it and it will be fine.

So you asked when you started racing Mr P..........how long ago was that.....LOL!!! Have you asked since

Seems as though, the correct fluid would be what the different friction material requires. They have different coefficient of friction, just like the fluid. Don't expect to find any quick info, I've searched on and off for years, and give up. Just like the 2 hours I wasted today. I use Raybestos Blue Plates and type F. I can read the lettering after 250 passes, with the correct clearance. If and when I know what Raybestos recommends, I'll consider changing.

I started racing a long time ago.. most likely when
you were young... but the last time I asked... about
8 years ago.. did they change the 727 since then..
if so I will look at hyd fluid.... again

seems like they all work about the same

"edited by Monte_Smith" - come on Monte, don't hold back.

I emailed Raybestos. The tech person said blue plate clutch linings were engineered for multiple fluids. Typical corporate response, vague, but telling. I'll stick to what has worked. Ademon is right. Seems they all are ok, in Raybestos eyes.

I'm using a +4 type synthetic lube over 200 runs, took trans apart to change gear ratio, clutches look nice a couple of steels had some hot spots, I changed them and put it back together. 10.00 high 9 sec car.

This is pretty simple. Automatic transmissions, regardless of make work the same. There are some bearings and some clutch packs. You have to lube the hard parts and the clutch packs still "bite". Years ago, you had Dextron and Type F basically. Dextron had friction modifiers in it, Type F didn't. So in a race trans, it was felt Type F would let the clutches grab better. In reality they obviously BOTH worked just fine but some builders preferred one fluid or the other.

Today, as with everything else, we have learned a lot. Parts are more precise, clutch material is better, coated steels and all sorts of other things to make the trans work better. We also have much better fluid. The lubricity is better, but so is the "bite". How do you do that........additives. So as a result, Modern fluids are much more refined. They let your "driver" pickup truck shift without you even feeling it, by slipping the clutches but not burning them, and when it's needed, can still lock up firmly to tow that trailer and lock the converter up. You slip the clutches much with old type fluid and the heat scorches the fluid and it's trash. New fluids are MUCH more resistant to heat, foaming, scorching and lubricity breakdown. Simply put, it's better. You want to run old school fluid because you always have and it's worked......fine. Nobody is trying to stop you. But modern fluid is simply better. In a harsh environment, like a race trans, with a loose converter(that makes heat, lots of it) small or non existent coolers, yet wanting to maintain max bite and good lube qualities. Which fluid you think is BETTER. I didn't said would work, I said BETTER.

Monty JD lists five hydraulic fluids. Which one do you you run?

I would like to know this answer my self.

So when we are talking friction and gripping properties and making it last on the track, how about a trans that sees more street duty and some weekends at the track?? I have always used the Dex style but am open to change for max trans life!! Thanks. I like the fact that there are some good people here who know their stuff!!

Never tried it. But I may, and looking at the specs, I would use the low viscosity Hy-Gard in a normal trans like most of us run. The viscosity numbers are very close to the normal ATF+4 and Type F. The regular Hy-Gard is quite a bit thicker. Would not be surprised if that is what is used in the real high horsepower units just for that reason.

Both of the Hydrau oils are higher viscosity than normal ATF, but the Hydrau XR is close. That may be an option also for the big power cars, but it's actually made for construction and forestry equipment.

Most use Hy-Guard or the Low Viscocity Hy-Guard. The Low Viscosity is a direct swap for most ATFs, except if you read the standards is MUCH more durable and maintains viscosity better at higher temps and that's what we WANT.

I would suggest the low viscosity for anybody wanting to swap.

We have run regular Hy-Guard and a lot of guys with Bruno's and Lenco Drives use this. The regular Hy-Guard will generally tighter your converter up about 200-300 on the stall.

Same question from me??

Been doing some reading it seems type F has a viscosity index rating of 169. Hy gard is 140 and hy gard low visc is 195. It also seems some guys use the heavier hy gard to tighten up their converter some and the low to loosen one up. Pretty interesting stuff.