+3 was developed for the computer controlled 604 trans. It turned into +4 for the later units.The original type a,dexron 2,and type f are the ones that turned into varnish in the 60’s and 70’s. Type f was originally used in trannys that had bronze frictions,it has less friction modifiers in a very old formula. It does give a firmer feel to the shifts in most cases. Any oil thin enough will operate an automatic,the trannys in our APCs used light motor oil. The friction composition is really what dictates the oil .
Having said that,any atf will work. Back in the Dex 2 and 3 days Transgo would recommend adding 30 wt to heavy duty units for added lube. I run dex3/ mercon in my 727 and it shifts plenty firm. The newer tfs have different friction materials than the older ones do,we put +4 in those. Bottom line is they all work in older trannies like ours,I’d stay away from the low viscosity oils like dex 6, the fluidics in our trannies weren’t designed for that thin oil.
Ain’t no magic oil,if your tranny slips,there’s something wrong with it.
Having said that,any atf will work. Back in the Dex 2 and 3 days Transgo would recommend adding 30 wt to heavy duty units for added lube. I run dex3/ mercon in my 727 and it shifts plenty firm. The newer tfs have different friction materials than the older ones do,we put +4 in those. Bottom line is they all work in older trannies like ours,I’d stay away from the low viscosity oils like dex 6, the fluidics in our trannies weren’t designed for that thin oil.
Ain’t no magic oil,if your tranny slips,there’s something wrong with it.
