Many here have argued that todays dino oils (Group III/Group IV) are very close to synthetic quality.
Can that be said of today's ATF fluids as well? I currently use Mopar ATF +4. How does it rate compared to a synthetic?
ATF+4 is a quality synthetic tranny oil. All ATF+4 labled fluid has to meet mopars standard. Which means that it's all the same fluid across the board between brands. So if you are using ATF+4 fluid it does not get much better.
Usually when we speak of dino base oil, we mean Group I and Group II. Group III is "full" synthetic but not "true" synthetic. Group IV, polyalphaolefin, is indeed true synthetic.
Only the most recent specs from GM and Ford have required ATF makers to move up to Group II base oil. ATF+4 is a Group III syn, as is Castrol Transynd for Allison transmissions.
There are no true synthetics licensed by DaimlerChrysler as +4, but some do a very good job, such as Mobil 1 and Amsoil ATF. The new universal additive packages for ATF are very good.
While I think some Grp II and especially Grp III ATF base oils are way ahead of the old Grp I ATF's, when you look at some of the temperatures of newer AT's I wouldn't touch anything less than a Group 4.
Check out the tranny forum (where maybe this thread should be), The Critic posted some Honda AT temps. Crickey that'll melt the chrome off a trailer hitch....