My dodge has 60,000 miles now and I've changed the trans fluid twice and the rear diff once and the engine every 4500 miles. It's impossible to change the fluids to often. New oil is better than any used oil. It's old wife's tales not to change if never changed.
I may just like old wife's tails...
2015 338RETS Eagle Premier gloss sides., king.
2012 Ram 3500, crew cab 4x4 duelly Deleted
16k miles, 530HP, 1000 +torque.