I will preface this post with saying I understand I have not properly maintained my transmission fluid.

I have a 2005 Acura TL A-Spec. I bought it with about 37k miles on it. It now has over 180k miles on it. The transmission always shifted a little firm and had a very minor shutter. Obviously these things have gotten worse with time. Very recently, within the past week, at about 45-50 mph when not accelerating, just cruising, the trans will go into over drive but will slip back into fourth gear and will make a not good grinding sound. If I let off the gas and then get back on, it stops right away. If I feel like it is coming on and I give it some gas, it doesn't happen.

Here is my question; to my knowledge the fluid has never been changed, no more than one time max. I've heard that changing it at this point will likely do more damage than good, but there is no turning back at this point. I did buy some Lucas Oil Trans "fix it" fluid to add into the swap. Lucas Oil has great products, but this may be beyond helping.

Any recommendations on the change? Is there even a trans fluid filter on my car? Any feelings on Lucas Oil stuff?

Like I said, I know this isn't good. I've maintained the shit out of the rest of the car. I do every oil change myself. Have replaced a radiator, power steering pump, water pump, I don't feel like this will be a big deal, but any pointers or tips are always greatly appreciated.

 

Anyone?

 

Your best bet is to replace the 3rd/4th gear solenoids. This can be done fairly easy as it only requires a 10mm wrench, and supplies to take off your front driver tire.

Then replace the fluid with either all of Redline D4 or mix it with D4 + Racing ATF.

In your case, I recommend doing Redline D4 6 QTS & 3QTS Racing ATF.

You will need to do 3 quarts (2+1) each time you change. Drive around 3 minutes or do it on your next oil change (the next 1x3).

 

So an update on this situation. I changed drained the trans fluid and followed the repair manual's suggestion of filling one quart, running through the gears, then filling half court intervals after doing the same thing. Instead of using three quarts of trans fluid I used two and a quart of Lucas Oil Trans Fluid "problem fixer". There is still a minor issue when going about 52 mph, but otherwise the trans feels 100% better. How long this will last, I don't know. I will most definitely be looking into the solenoid replacement though, thank you for the suggestion!