Please keep looking into this... I did tons of research online about gear oils and standard oils and the differences between the two (which isnt much). From everything that I found, the only difference between the straight weight and multi-weight oils is that the multi-weight oils can adapt better to temperature differences. And for us living in the midwest, I would have to say using a oil that can adapt to the severe weather changes we deal with would be better than a straight weight oil that may get extremely gooy and thick in -20degree weather. Not saying that it will cause issues with the transmission, but having an oil that will stay at a closer consistency from 90degrees+ down to -20degrees may be better for a us.
Will the synchromax help more for smoother shifts and more protection during the hotter summer days? Damn straight! But the other thing were not looking at, is that we also have to deal with extreme cold in the winter... I think that majority of people here are driving their darts as their daily... that being said, I think many people are over looking the fact that the same synchromax that is AWESOME during the summer is going to turn into a gel-like goo during the winter and be very difficult to warm up. Now, if youre cool with losing MPG and having a stiff and sticky transmission for a while till it warms up, then go for it! You should have no issues. But for those of us who want comfort all year long and a good oil that is going to help with the smoothness and protection for the tranmission, I think the gear max is the way to go.
The other thing that I found is that the Mopar gear oil does NOT have special additives in it due to the style of the synchros... As far as I could find, neither does the gear max. It states that they have their proprietary "friction modifier formula" but that seems to come in ALL Royal Purple oils... Again, I understand that the Master Techs say that youre not supposed to use anything but the manufacturers own design for everything on the car... But when has that stopped anyone here from doing something different? I honestly cant imagine that the Dodge dart has THAT special of a transmission to where if you use something other than the Mopar brand oil and or a straight weight oil that it will have issues. But then again, I have been wrong before...
So, keep us updated with what you find! I'd like to hear exactly why we cant run something from a company that states their gear oil is warranty spec.