1999 Toyota Camry, 4-cylinder, automatic
153,000 miles
After my last oil change, my mechanic noted my transmission fluid was discolored, and recommended a transmission flush. He also said it should have been done three times by now. I don’t recall if it was ever done when I was having regular warranty service at the dealer, but my practice has been to add fluid when it was low, which is very rare.
Is flushing different from merely draining and refilling? Do I need it periodically flushed? I have heard that this can possibly cause damage to the transmission. Any experience here?
If you want to change your transmission fluid, you’ll need a flush. Draining and refilling only changes about 30% of the total fluid.
Fluid definitely gets dark-colored by around 30k miles. I don’t know just how much its qualities deteriorate, but I have a car mechanic friend who strongly recommends a full flush every 25-30k miles, and I follow this advice.
Take care that the fluid added exactly matches the manufacturer’s specs.
Please refer to my posts in the thread that Sapo linked for some basic info and answer to some of your questions.
My info shows that the maintenance recommendation for normal service is to inspect the tranny fluid every 15,000 miles. Implicit in this is to replace it as needed based upon said inspection. The recommendation for severe service is to replace it every 15,000 miles. Practically speaking, replacement every 30,000 miles makes sense for normal service. Part of the idea is to replace it before it has deteriorated significantly.
This brings us to the question of whether and when it has ever been serviced, and just how bad the fluid is. I would think that the dealership would have serviced it at 30,000 mile intervals, but to be sure you’ll need to review your service records from them. If the fluid is dark brown or black, it’s possible that an infusion of fresh fluid will push it over the edge of the cliff that it has been hovering on, necessitating an overhaul. (Note that the need for the overhaul would be significant internal wear, not damage caused by the fresh fluid. Fresh fluid merely exposes the wear already suffered.) If the fluid is not that bad, then a service would be called for.
As to whether it would be better to do a flush (changes almost all the fluid, but doesn’t address the filter) or a traditional service (includes new filter but only replaces about 2/3 of the fluid), it’s hard to say. My opinion is that if the filter has over 60,000 miles on it, it should be replaced.