I'm looking to change my trans fluid and would like to know if anyone is currently using Shell Spirax S3 ATF MD3. My truck is a 2001 F25 7.3 205,000 miles with the 4R100 transmission rebuilt at 178700 miles and a transco shift kit installed. I pull a 12,000 lbs 5th wheel to CO and around TX. Any info on the Shell or other suggestion will be helpful.

 

We buy that same Shell ATF by the 55 gallon drum and use it for all Mercon/DexronIII applications in vehicles and equipment. It is a quality oil that I wouldn't hesitate to use, unless switching over to a full synthetic.

 

Looks like it is Shell's Dex/Merc grade ATF. Your 4R100 will run just fine on it.

http://oilmart.com/data/products/pds...0ATF%20MD3.pdf