Best oil for my T-5?
 

Castrol SLX or???

I used Mobil 1 synthetic ATF in mine.

The guy that rebuilt my t-5 says he doesnt recomend synthetic, but i would use it anyway if it fits the budget (4.99 qt) i think, but i use penzoil type-f, i know ford recomends dexron/mercon, but you can use type-f, and a t-5 builder i know, says it creates less heat.

i also use mobil 1 synthetic, since it was new and no problems to date

Red Line Oils are good But not to cheap

I have run Mobile 1 synthetic ATF and Redline synthetic ATF in mine, both work well.

first time i was told to put automatic tranny fluid in my t-5 i thought the guy was nuts. but, it is appropriate, weird, huh? i had an s-10 truck with a 4 speed (like an 83 or something) and it used 50 w gear lube.