Over the last year, I have researched - looking at car servicing sites, Toyota sites, asking questions and no one seems to have the answer.
I have a 2004 Toyota Avalon which now is driven about 3,000 miles a year. It has 112,000 miles on it. For a number of years, I drove it like the average driver. 15,000 miles a year. Mostly city miles. Some highway miles. Always partially drained the transmission a bit earlier than recommended in the manual. No problems.
Now, I put about 3,000 miles a year on the car, mostly 1-2 miles and stop. Then to somewhere else 1-2 miles and stop. So, the ultimate question is how often or how many miles to go and then partially drain the transmission and put on a new pan.
I already know that the car rarely is warmed up. I already change the oil once a year for that reason.
I know that the stop and go is considered severe driving. Some people use a formula that city miles are 10 times harder on a car than highway miles. If my service manual assumes a lot of high way miles, the recommended 40,000 mile servicing is met in about 2.5 years by the average American driver who does highway miles.
I am guessing that there should probably be a partial drain about every three years.
1. I always use the Toyota fluid.
2. I know that color is only a partial test for when there should be a partial drain.
3. I never want to use the smell test to figure when to do a partial drain.
Why my concern? I want the car to go more than 200,000. 3 other Toyota Avalons of the same model and release in the family did over 225,000 miles each.