Oil/Fluid For T5?

[horseballz]

Questions for the Gurus,
When I had my 1990 T5 looked at (boiled out,new rear seal/bushing, new steel front bearing retainer, inspected, couple new syncrhros, otherwise clean bill of health) I was told to use only synthetic oil/fluid. I thought it was supposed to be ATF fluid but I think I might have heard wrong/be mistaken? All the parts house books/computers call for like 80 weight. What's the real poop?
Thanks Much,
Gene

 

[rbohm]

good info on the T5 can be found here;

Modern Driveline - T5 History in Ford Mustangs with specifications for World class and non-World class T5's

and dont forget to read this at the very bottom of the page;

One last piece of important information. ALL World Class T-5 use ATF oil and NOT heavy gear oil or Redline MTL! All NON-World Class T-5 use 70 wt gear oil. We recommend high quality Synthetic oil as it lasts a long time and over a larger operating temperature. It is important to change the oil in your transmission based on how you use the vehicle. If the vehicle is your daily driver then changing the oil every two to three years is fine. However, if the transmission sees regular track duty and pushed hard, then once or twice a year is in order. When we rebuild transmissions, we can tell when the oil has been changed often as the parts are much cleaner with less over all wear. There is no filter inside the manual transmission only a magnet at the bottom to pick up the metallic particles in the oil, the only metallic parts in a transmission is the gears or bearings. Oil is cheap, transmissions are not!

 

[horseballz]

rbohm,
Thanks for the link. Even that paragraph that you quoted still leaves room for confusion:

"One last piece of important information. ALL World Class T-5 use ATF oil and NOT heavy gear oil or Redline MTL! All NON-World Class T-5 use 70 wt gear oil. We recommend high quality Synthetic oil as it lasts a long time and over a larger operating temperature."

They do not specify if they are recommending the synthetic for the 70 wt dino oil or for the ATF! I have been reading vehemently good and bad reports for both sides of the standard ATF and synthetic ATF fence. I just want what is going to work best. Maybe I'll call Modern Driveline tomorrow for clarification.
Thanx Again
Gene

 

[rbohm]

gene, synthetic or not, oil is oil, and as long as you use the proper weight or type of oil, you are good to go. the only difference between dino oil and synthetic is the molecule chain. dino oil molecule chains tend to unravel when they break, where as synthetic oil molecule chains dont. this is what gives synthetic oils their film strength advantage. go ahead and use a good synthetic oil in your T5, it will actually be a big help. and yes there is synthetic auto trans fluid.