i was told +4 can be used inplace of +3 is this true?

 

Technically yes, but depending on what trans you put it in you might get mushy shifts. +3 is a semi-synthetic and I believe +4 is full synthetic. +4 is supposed to be better. It lasts longer, has a higher boiling point and a better coefficient of friction (more slippery). The bad: it stinks, it hard to get the greasy feeling off you hands and the dye goes dark quickly making you think the fluid is dirty. I run it in my transfer case but use +3 in my trans. some Chrysler's require a trans computer reprogram to upgrade to +4 because of it being more "slippery"

 

from what i understand it was designed to be backwards compatable, and i was just told by my parts guy a few weeks ago that atf +3 was no longer going to be available....rebuilt my trans with +4.

 

Dodge says this. ATF+4 has now taken the place of ATF+3. So, +4 in place of +3, but never +3 in place of +4.

 

cool thats what i kinda thought +4 in place of +3 but not vice versa

 

TSB 21-010-06

http://dodgeram.info/tsb/2006/21-010-06.htm

 

you can read all about it here...
http://www.allpar.com/mopar/transmissions/fluids.html