[Land-speed] Which Automatic Transmission Fluid for Racing

[ifixmgs at cox.net]

Mobil1 has become  the trans juice of choice for most folks who tow big horse trailers,  and full time  RV'ers (who are mostly anal about maintenance)  all swear by the stuff.  I can't imagine any automatic  trans  getting a harder workout than a loaded  bus-sized travel trailer  or a   maxed out combo four-horse-sleeper trailer being hauled across the desert or over the the mountains, or in stop and go traffic in hill country on a 110* day.   

I use Mobil 1 ATF (and oil)  in my  '90 Suburban which hauls a portly  28 foot steel dual axle horse trailer.   We got a  "whopping"  20%  difference in fuel mileage (9 mpg  all the way to 11 mpg... ). But it definitely shifts smoother and does a far better job transferring heat out of the trans and releasing it at the cooler.  I've only changed the filter and fluid once, after about 50k miles, and there was far less pixie dust in the pan than there was at 30k when I switched to Mobil.     
   
The only application I know of  where   synthetic ATF has been  problematic is  in  T-5 gearboxes (possibly others) .  I used a quart of B&M Trick Shift (unaware that it was synthetic) in my drag car.   After suffering missed shifts, and realizing the problem,  we tried a drain and refill but wound up taking the trans apart, rinsing it out with solvent and switching to petrol based before the problem completely went away. Synthetic must be very slippery compared to conventional ATF. 

My diff lube of choice  is SWEPCO 201  synthetic  racing diff lube - I won a 22 gallon drum of the stuff in 2001 at an NMRA event.  It's pretty pricey -  about $28 a gallon  then,  and  $40 now, but I've come to swear by it.  I used it in a screaming- loud Frankland quick change in a neighbor's hot rod  that had worn bearings and  wobbly  gear shafts, and it has remained eerily quiet.   It also silenced an early MGB banjo rear that had  bearing rust-damage from having been submerged in water without being properly drained and cleaned out.   My original plan was just to use it to get the car driveable, but after 5 years, it's still quiet even at 70 mph.  
 
Mark C 
at the edge of the Great Dismal Swamp

---- Doug Odom <dlodom at charter.net> wrote: 
> I like the way the inside of my TH-350 looks when I take it apart. I use the 
> Mobil One Synthetic ATF. In fact I use Mobil One products in the motor, 
> trans and rearend.      Doug Odom in big ditch
> 
> 
> ----- Original Message ----- 
> From: "Dick J" <lsr_man at yahoo.com>
> To: "lsr list autox" <land-speed at autox.team.net>
> Sent: Sunday, April 20, 2008 1:39 PM
> Subject: [Land-speed] Which Automatic Transmission Fluid for Racing
> 
> 
> > I'm inclined to go with Mobil One Synthetic high performance automatic 
> > transission fluid in the new TCI TH-350 in the racecar.  Anybody got any 
> > other thoughts about ATF?
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