I have a 98 accord 4-cyl with 132k miles. Owners manual suggests drain and fill every 30k. That seems too long. Should I drain and fill every 15k to be on the safe side or at 30k as the manual says? So far, the transmission shifts perfectly at 132k and I have been using Honda fluid every 30k.

 

It won't hurt to do it @ 15k intervals. Thats what I would do.

 

15k and you should consider a complete flush too:
Provided by another forum member. I cannot remember his name and he WILL flame me!
Honda Auto-Trans Flush = 1 case (12 qrts) Honda ATF aprox $50. 1 new drain bolt washer $1.
1) Put the front of the car up on jackstands with the wheels off the ground. Put a large container under drain plug.
2) Remove the transmission drain plug (3/8" drive ratchet works fine). Let transmission drain and wipe sludge off drain plug.
3) Reinstall drain plug and snug (not tighten). Fill transmission with three quarts of ATF.
4) Start engine and shift into drive. Gently accelerate and let transmission upshift through the gears (don't go over 50 MPH).
5) Step on brakes and bring speedo to 0.
6) Shift into reverse and accelerate to 20 MPH.
7) Bring speedo back to 0 with brakes. Shift to park and shut off engine.
8) Repeat steps 2 through 7 TWO MORE TIMES.
9) Drain the transmission once more. Reinstall drain plug and tighten firmly (don't forget to reinstall crush washer).
10) Remove jackstands and put vehicle on level ground.
11) Fill transmission with 2 1/2 quarts of ATF. Start engine. Shift to drive, then reverse, then put back in park and shut off engine.
12) Check transmission fluid level. Top off if needed to bring fluid level to the top of the crosshatch marks on the dipstick.

 

Or you could do it alot simpler and dis-connect the tranny cooler lines and find out which is the feed and witch it the drain. You will run the drain into a bucket or pan, then the feed into a bucket that you empty 10qt's of tranny into. Then start the car. The tranny pump will auto matically drain the fluid into the empty bucket and pull in the clean fluid as if it were a closed system. Continue till all the clean fluid is gone. then turn the car off and let sit for a min. or two. Then take a can of brake cleaner and spray out the tranny cooler with it. This will clean out the cooler. Last few steps are to connect the drain tube back to the tranny cooler then start the car for between 15-30 sec's this will get out any brake cleaner out of the tranny cooler. Lastly connect the feed line back to the cooler and start the car for about a min. Put the tranny through all the gears and the back in park and turn off. Check fluid level and add as needed to top off. Much easier and quicker, IMO