I have a 2005 model Vitz, old shape, engine type 1SZ-FE. When the car is in drive "D" suddenly it starts changing to "2" and then back to "D", and to "2" then to "D" again (just like flashing), does this for a few seconds and stays at "D" afterwards. Showed it to a mechanic, he said that the gear oil is too thin and low, needs changing.
Question is, whether the mechanic is right? If yes, which gear oil to use, how much to use and is the old shape Vitz CVT or ATF?
Get the Gear shifter cable adjusted it get loosed in those old trans. Your problem would be solved dont mess with the viscosity of ATF. Or you will end up in a dead street by transmission failure due to CL pouring in the atm.