Transmission oil is easy to check, every 5 thousand miles or so take a couple drops and drop it on to something white plastic like a plastic spoon. When you see the color start to change or get dirty you know it's time. Works better then just checking the paper towel after cleaning the dipstick, because you can see the color better. It should always be the bright light red. Redline makes the Dodge (Chrysler) specific fluid called C+ATF, it is important to use the exact fluid for the tranny. Redline also has a couple options for gear oil, one is Shockproof for heavy use, and the other is their standard gear oil which is rated as good as anything. Check the reviews on this stuff online. Using group 5 oil will keep those parts cooler during operation and will last at a minimum two times as long as factory oil, according to oilstop. In the gear application I wouldn't be surprised if at 100k miles Redline gear oil is working as good as the day you put it in. It really comes down on how you use your stuff.