I am now on my 4th TL, having owned a 2001, 2001, CompTech 2002 Type-S, and now the TL 5AT. Towards the end of my ownership, the 2002 started showing signs of the transmission flare. Having been a member of here a long while, I knew all about the history of the trannies, so off it went (sold it back to the dealer - heh heh).

Now, I have scanned a lot of the background info on this issue, and several things jump out at me as an engineer:

1) Heat seems to be part of the equation
2) Varnished parts wreak havoc in modern auto trannies
3) A revised lubricant spec was considered by AHM at some point
4) The total liquid capacity of the tranny is small for a 270 HP car - much less than my 168 HP Outback.

So where does this lead me? Well, my recommendation is to consider running a synthetic tranny fluid. Although I think that synoils are over-hyped, and today's hydrocracked mineral oils are nearly as good in many respects, synthetic ATF is a good idea.

1) The synthetic fluid both pulls and releases heat more effectively than mineral-based oils
2) It resists oxidation and the attendant varnishing of small valves far better
3) It has higher film strength

But Honda recommends only its Z1 formulation. Is there a synthetic that expressly meets that spec? The answer is yes: http://www.amsoil.com/products/atf.html

Amsoil Tech Services directly answered in the affirmative my inquiry, as to whether it would apply its lubrication warranty if any tranny failure was deemed to be fluid related. Based on my experience, if the fluid looks red, you are OK, as most labs cannot determine the basestock of the fluid anyway.

The drain and refill are simple matters: 3 qts of the total 7 come out per drain, so the first drain leaves about 50% of the factory fill, the next 25%, etc.

I plan to do this at the first oil change. I will also perform a careful analysis of the fluid, looking for precursors of wear.

 

Thanks for the info. In keeping with the hypothesis of heat being the enemy, does it make sense to add a tranny cooler as well? Do they even make one that fits the 04 TL?

 

The tranny has a filter and a cooler already - you could series in another one, but you will see some pressure loss - that is why I recommended fluid - it has no possible side effects.