Should a 1998 with 120,000 miles have the transmission oil changed.
Yes, for the fourth time.
However, if the OP didn’t have it done at 30k, 60k, and 90k, then it may be too late if the transmission is already showing signs of slippage.
OP: can you confirm whether you have an automatic or a stick.
It doesn’t matter.
I should be changed.
Tester: at what frequency do you recommend for a manual?
It depends on manufacturer and use.
Pretty sure that’s not true, at least the 30,000 number for ‘most manufacturers’
ATF should be changed about every 30 to 40k miles (more often depending) even if the car maker says differently; including that “lifetime fluid” recommendation. Agreed; in the OP’s case it’s due for the 4th fluid change.
The way I look at it is that if a car maker says the fluid is “lifetime” then the warranty on the transmission should also be lifetime. Put their money, not the car owner’s, where their mouth is.
As I’ve mentioned previously, a long time friend of mine runs a trans shop which he took over from his dad decades ago. He sorts out trans problems and rebuilds them 5 and sometimes 6 days a week. He has stated more than once that almost every transmission failure he runs across is caused by not changing the fluid regularly or by running the fluid low due to a leak.
I’d say change it, even if it’s past due, could be a case where it helps the tranny live for another 120k.
I believe it. I have never had to overhaul the trans on any of the cars that I have owned over the past 50 years. On the other hand, I have known a few people who have had to do it at somewhere between 80k and 120k. The difference between my cars and theirs is that mine had the trans fluid changed every 30k or so, and theirs were never serviced.
A drain and refill should still be fine, just not a flush. If it’s slipping, yes, it won’t cure the matter, but it may buy some time.
And I’m not saying that you’re suggesting this here, but OP don’t listen to anyone who says you shouldn’t drain/refill at this mileage because it will cause more damage. If that were to happen, it just means that your transmission was basically running on very borrowed time, and could’ve conked out any day just driving down the street; better to have it happen under circumstances which you can control.
On that, we can agree.