Similar to engine oil, transmission fluid in your Honda CRV breaks down chemically over several thousand miles of use and loses its ability to lubricate key components in the transmission. The transmission fluid also gets contaminated from the clutch packs' wearing which, if unchanged, can cause damage to the transmission. If your transmission is shifting harshly, it is most likely an indication that your transmission fluid needs replacing. Replace the transmission fluid in your Honda CRV every 30K miles to keep your transmission working properly.
Jack up the Honda CRV and place on jack stands.
Place a drain pan below the transmission oil pan.
Loosen the transmission oil drain plug from the transmission oil pan with a ratchet and let the fluid drain into the drain pan.
Tighten the drain plug back into the transmission oil pan with a ratchet once the fluid has drained out fully.
Lower the Honda CRV to the ground.
Remove the transmission oil dipstick and place a funnel in the fill tube. The fill tube is the same tube that the dipstick is in.
Fill the transmission with four quarts of transmission fluid.
Reinstall the dipstick in the fill tube.
To completely flush out the transmission, you will have to replace the transmission fluid a total of three times. This is because not all the transmission fluid drains out of the transmission when you remove the drain plug; some of the fluid will remain in the transmission. Replace the fluid and drive the vehicle for a week. Replace the fluid again and drive for two weeks. Then replace the fluid one more time.
Wear safety glasses while working on your Honda CRV.