As long as there is some "fresh" fluid in there, I'm good with that.
It's interesting how much psychology is tied into transmission fluid changes.
Black fluid is a no no, but diluting the black with a few quarts of fresh fluid and giving it a hint of pink, I'm good with that.
I'm not picking on anyone, just an observation about these tranny fluid posts.
Here are my thoughts:
- Lifetime fluid almost certainly means lifetime of warranty.
- Many 4Runner owners are apprehensive to do the full flush due to the increased complexity over the drain and fill. I think people are afraid of making a mistake on a high dollar mechanical part that is the transmission. It sounds like those that have actually done the flush, report that it wasn't overly complicated.
- Drain and fill is most likely better than never replacing it at all.
- In the automotive world, there seems to be anecdotal evidence of correlations between tranny fluid replacement on very high mile transmissions and tranny malfunction/failure. This could partly be that people over/under fill the transmission and partly could be that the transmission already has a lot of miles (a high mileage transmission is more likely to fail than a newer lower mileage transmission, and transmission replacements typically occur on transmissions that have higher miles).
I'm still on the fence, but eager to continue to listen to opinions.
Some basic math (from what I understand, the transmission holds about 12 quarts of fluid and the drain and fill requires about 3 quarts).
1 drain + fill will get you 25% new fluid (3 new quarts)
3 drain + fill will get you just over 50% new fluid (9 new quarts)
5 drain + fill will get you just over 75% new fluid (15 new quarts)
8 drain + fill will get you just under 90% new fluid (24 new quarts)