From the January 2008 Honda ServiceNews:
Remember, performing a "flush" as outlined by the above procedure is not necessary if you are just performing scheduled maintenance.Some A/T repair procedures call for flushing the trans using Honda Genuine ATF-Z1 (and no substitutes). Problem is, where do you find the info to do that? It’s not listed in the S/Ms, and if you do an ISIS search, you’ll find a few ServiceNews articles on this subject, but they’re rather dated, and none of them say the same thing. Even the most recent one (see “Revised A/T Flushing Procedure” in the December ’00 issue) still mentions that old work horse—the PGM Tester—which we stopped supporting when the HDS first came on the scene.
NOTE: The term “flushing” refers to repeatedly draining and refilling the trans with Honda Genuine ATF-Z1. Don’t confuse it with aftermarket flush systems. American Honda still strongly recommends that you avoid using them on any Honda vehicle. The original procedure was written for simpler A/Ts that readily upshifted when you ran the vehicle on a lift. But A/Ts have come a long way since then, and most of the newer ones balk at shifting past 2nd gear when on a lift, unless you work the shift lever a certain way. In light of all this, we thought it was high time that the A/T flushing procedure got a facelift. So here’s the latest word on flushing that works for all A/Ts:
1. Set the parking brake, and raise the vehicle on a lift.
2. Drain the trans, and refill it with Honda Genuine ATF-Z1. Refer to the applicable S/M or to ISIS for details.
3. Start the engine, shift into Drive, and release the parking brake.
4. Push down on the accelerator pedal to raise the vehicle speed to 2,500 rpm.
• If the trans shifts past 2nd gear, go to step 5.
• If the trans won’t shift past 2nd gear, keep the engine speed at 2,500 rpm and shift from Drive to Neutral and back to Drive. Then go to step 5.
5. Make sure that the trans shifts through all the forward gears and goes into torque converter lockup.
6. Let off the accelerator pedal, and press the brake pedal to drop the vehicle speed to zero. Shift into
Reverse and then into Neutral.
7. Shift into Drive, and repeat steps 4 thru 6 four more times.
8. Set the parking brake, and repeat steps 2 thru 6 two more times.
9. Drain the trans, and reinstall the drain plug with a new sealing washer.
10. Refill the A/T with ATF-Z1.