• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

What transmission fluid to use

malex

FBBO Gold Member
FBBO Gold Member
Local time
3:52 AM
Joined
Aug 10, 2013
Messages
2,385
Reaction score
3,546
Location
Canada
Guys. Going to change the trans fluid and I'm looking for recommendations on what's best to use please. For the 727, bracket racing, with a trans brake. What works, what's best.
 
Info that came with my Cope valve body says use type F, so’s that’s what I use.
 
Dexron Mercon 5.It’s designed to replace type f and previous fluids. All I use now for the last 12 Year’s no issues at all. It’s every where when you need it.
 
I do not race but have been using 303 hyd fluid in my 727 and think it shifts better, there is a ton of info on it on the web and the kicker is 5 gallons for $40 or so at tractor supply, drawback is it is clear and hard to see on the dipstick.
 
for racing, my vote is type F

Is anyone using synthetic trans fluid? Any experiences with that?

Back when I used to manage a large fleet I would get salesmen coming in all the time but I couldn't justify it because of the cost and no/low trans failures using conventional.
Could be the same thing here??
 
My friend who just recently retired from the transmission business claims atf+4 is best for any mopar old or new.
 
My recommendation is SYNTHETIC.
I use synthetic....I suggest any quality of BRAND NAME synthetic.
Also I use MARINE SYNTHETIC ATF because it has additives to fight moisture in the tranny. And we store these cars during cold and damp times of the winter...the marine synthetic has the additives to help with these conditions...especially if you fire up your car in the garage or driveway when it is cold outside and then put it back into the garage. When it cools down there will be moisture form. Start up your motor, pull it back into the garage, let it cool down and then pull a valve cover and look at the moisture build up...I would guess the same is going on with the transmission.
I personally spoke with one of the technicians at one of the transmission fluid manufacturers and he shared with me that using the Marine Synthetic in my race car would not have any bad effects...he said it is the same fluid as regular Synthetic ATF only with the addition of the moisture fighting additive.
 
Last edited:
Lots of good information here guys, thanks. I'll be dropping the pan in the next day or few and will see how it looks inside. Could be posting some pics of that pending inspection but I'm not expecting any surprises.

I'm sure finding lots on the net about type F being the fluid of choice.
 
I have F in mine. When I had the 8” converter in though I had JD Hy-Guard in it. Barney ET’d and MPH’d better then.
 
I just use DexIII in mine .
Service once or twice a year .
I finally am replacing the transmission , nothing wrong with it , with a Tbrake unit this week .
The old trans was in for 10 years daily driver raced at least once a month . In all that time it broke 2 front flex bands on the street and rebushed the front pump .

Tex
 
I just use DexIII in mine .
Service once or twice a year .
I finally am replacing the transmission , nothing wrong with it , with a Tbrake unit this week .
The old trans was in for 10 years daily driver raced at least once a month . In all that time it broke 2 front flex bands on the street and rebushed the front pump .

Tex
Hurrah !!! Another TRANSBRAKE INSTALL.....LOVE IT.
 
I have F in mine. When I had the 8” converter in though I had JD Hy-Guard in it. Barney ET’d and MPH’d better then.

I recall we talked about this last summer too Wooks. Do you think the faster ET and MPH had to do with the fluid?
 
I just use DexIII in mine .
Service once or twice a year .
I finally am replacing the transmission , nothing wrong with it , with a Tbrake unit this week .
The old trans was in for 10 years daily driver raced at least once a month . In all that time it broke 2 front flex bands on the street and rebushed the front pump .

Tex
Thanks Tex. I used a dexron III equivalent by Shell this past season and it worked ok for me too. Hoping to see a clean pan when it comes down.
 
It helped because the 8” is not ideal for my application. It works but a band aid fix to a poor converter adjustment.
 
Update. Dropped the trans oil today and it wasn't good. Dark, tainted with metallic grey and odor is stronger than it should have been. Really it was a mess. It has to come down and gone through.. This trans came with the car and was said to be fresh, fully rollerized and so on. Looks like I'm going to find out how trick this trans is soon enough.

Oil is dark, tainted with metallic grey
IMG_1969.JPG

I wiped the pan out but the metallic remains visible
IMG_1970.JPG

Completely not what I was expecting to see.
IMG_1971.JPG


IMG_1972.JPG


IMG_1973.JPG
 
Malex, I am looking at one of the trans pictures posted above.
Do your header collector extensions REDUCE the size of the collector flange on your headers ??
 
That’s what mine looked like the first time I dropped the pan.
 
Auto Transport Service
Back
Top