Hello all. I'm a car guy (Dealer trained GM, Chrysler, Alfa Romeo and even Mitsubishi in the early 90's) and I'm trying to help my niece who lives 3000 miles away. 2003 Lancer, base engine I assume. She says that "the transmission is beginning to slip between 2nd and 3rd gear upshifts". Fluid level is good. About 100k on the odometer, fluid never changed. Is there a consensus here on changing the fluid and filter, or not changing. Adding a snake oil like TransX? Don't laugh, I've had great results using TransX. Any and all comments, questions, suggestions welcomed. Thanks.