My cousin is buying an 04 Accord 4cyl with a little over 100k miles. More than likely the trans fluid is what the factory put in. Afaik the 4cyl AT's are stout, but I'm still concerned about whether swapping out all the fluid in one shot will do any damage. 3x3 method will get almost all the old fluid out. Planning to replace with Honda DW-1. Fwiw, here's Honda's procedure: 1. Set the parking brake, and raise the vehicle on a lift. 2. Drain the trans, and refill it with Acura Precision Crafted 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.