I have been noticing that my 91'' Olds Cutlass is about 75mph, the overdrive finally kicks into gear, how does one adjust or replace out a part??? to resolve this situation, or is this a sign of old age, with 174,000 miles( have not replaced oil yet or filter???is it worth to do so?)

 

there is a shift cable on my 91 supreme that can get out of adjustment or in my case the plastic housing got brittle and broke due to overheating at some point.if it isn''t broke all you have to do is find the cable at the throttle linkage and there should be a button you push in all the way then without the car running push the throttle all the way to the floor and it should self adjust.In my opinion a trans isnt bad unless its slipping.