question on "universal" ATF that covers all specs

[friendly_jacek]

Originally Posted By: DWC28
A few ATF specifications. Some are mutually exclusive.

Viscosity @ 100C (cSt)
MERCON SP 5.5 min. and 6.0 max.
MERCON 6.8 min, no max
ATF +4 7.3 min. and 7.8 max.
DEXRON IIIH 6.8 min no max
DEXRON VI 6.4 max. no min



While this is true, we do know Dexron III/Mercon shear down to Dexron IV/Mercon SP levels quickly. Besides, viscoty varies with temps, so it's not critical. I would be worried more about friction/shudder properties.

 

[SilverGGA]

https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=1648543

I did some research on Ford Mercon V vs Mazda ATF M-V. The conclusion was for those 2 specs, it was physically impossible for 1 fluid to meet both beccause they required a different viscosity at a low temperature. The allowable viscoity at that temperature probably have no overlapping range since Mazda intentionally defined a separate spec and released a TSB specifically on this topic.

This is exactly why I never use universal ATF that claims to meet all specs under the sun.

Will it work? It might.
Are they the same? [censored] no.