2003 Lexus GS430, 15,607 miles, Toyota Type IV ATF

[btanchors]

Here is a UOA of my 2003 Lexus GS-430 Automatic Transmission. This oil was in use for about 2 calendar years, so it was mostly short trip driving - I don't put many miles on this vehicle. Based on these results, I'm going to let it go 3 years until the next change. Comments?

 

[raytseng]

Because the easiest and cheapest drain fill service doesn't remove all the fluid, but only 2qts/10qts, you should be proactively replace the fluid before it even comes close to registering as bad.
This changes the strategy you need to use compared to engine oil.

A corollary is why do people obsess over getting every single drop of "old" oil out, and letting their oil drain? If your old oil was that "bad" and puts you in a situation that you want it ALL out; that means for you were already driving on "bad" oil, which you should've already changed out much sooner anyway. If you're in that situation with your ATF, now you got a problem since it is only "easy" to get out 2quarts at a time.

The complexity to do a full fluid replacement is more costly and troublesome to do as a DIY, so keeping on top of the maintenance with just simple drain/fills to refresh the ATF before it even gets bad is the better strategy, even if you're throwing out oil that's numerically 80% good as new.


Anyway:
Toyota T-IV is relatively cheap, an ATF drain/fill is arguably simpler than an oil change and if you DIY, it is not expensive.
The owner's manual I believe says do a drain/fill every 30k miles only for severe service, and 60k for regular service.

But due to the inexpensive nature of this service, and expensive consequence, you can just do it every 30k, even if you're regular service car.

People who know they have questionable ATF, either spend more to do a more complete "exchange" to kick off their maintenance, or just frontload and increase the frequency of their ATF change coinciding with every OCI for a couple of years then tapering down.

 

[raytseng]

So, just consider what you're trying to accomplish.

If you're aggressive with your maintenance, After 10years, you're out an extra 6quarts of T-IV at $5/quart? For a smoother shifting car?
Good tradeoff in my opinion.

 

[Artem]

Drain n fills where only two quarts come out of a total capacity of 10 quarts is a waste of time and money.

I suggest a PROPER oil change through the oil cooler line and replace ALL the old oil with new fluid. You verify this by continuously removing / replacing 1 quart at a time until NEW oil starts coming out of the line.

 

[raytseng]

I think you threw out the term "waste of time and money" willy nilly; but your point is taken.


Yes, if you know how to disconnect an oil cooler line and change the fluid, that is more efficient method to change fluids, but then I'll argue again, why did you wait for all the ATF to get so bad that you require changing all of it.



D/F methodro: Easy to do, fast and easy if you coincide with an Oilchange. Low cost. DIY-able. Cons: Wastes some fluid, may have to do multiple times, but fluid is cheap.

Oil Cooler line replacement: Pro: wastes less fluid, changes more fluid at one time. Cons: More time for the service, requires higher skilllevel, Can be costly if you are not doing it yourself. Potential that changing all the fluid in one go causes issues; but that's somewhat of a debatable urban legend if the transmission was in good shape to begin with.

The question on this technique though still is:
Why did you wait for fluid to be degraded to an unserviceable state to decide all of it needed to be changed? It doesn't suddenly change from good to no-good.


So my point is "it's not a waste of time and money", the time and money cancel out with skill, It's more of a draw depending on your skill level. Lexus and Toyota Engineers and the service manual think drain and fill is the Proper technique. If you want to argue with the designers of the car, fine you're smarter than them.