Changing MT fluid in a Prelude seems difficult at first. But if you've done it even once, it's no big deal. The biggest problem is getting to the fill hole which is located under the car and not as convenient as, say, the oil fill hole on the valve cover.
I recently changed the MT oil on my '92 Si (H23A1) and took some photos along the way. I'm not sure how other model years are configured, but I'm sure they're not too different.
You should also find out the exact capacity of your trans because it's hard to check the oil level. My '92 MT5 trans (H22 and H23 MT's have the same capacity) takes exactly 2 qts of oil so I know after the oil change that I'm up to specs.
Honda recommends using their MT brand, or 10W30 or 10W40 motor oil (SF or SG grade). I used Red Line MT90. You'll need exactly 2 quarts (1.9L) on the H23A1 or H22 engine. Be sure to use new aluminum washers on the plug bolts, too. The filler bolt is big, like 5/8 inch or so, and the drain is 1/2 inch I think.
NOTE: Honda recommends changing the manual transmission fluid every 30,000 miles or sooner under severe driving conditions
Here's the play-by-play:
Tools you will need:
3/8 inch socket set and wrench; oil filter wrench; torque wrench
You'll need to fabricate a special funnel to reach from the engine compartment down to the filler hole. This is the tricky part. Here are some that I made-up: (Photo 2)
I bought the long, metal funnel at www.harborfreight.com.
This one worked the best because it's easier to snake toward the fill hole. You might find it at an auto supply or hardware store. I had to add an 8 inch extension to the tip using a piece of 1/2 inch tubing to make it reach into filler hole.
The other type is just a regular funnel with a 2 foot length of 1/2 inch tubing pushed onto the tip. You can find the tubing at a hardware store or pet store that sells pet fish (it's used for the filter systems). Get stiffer tubing. It's easier to snake through the engine compartment.
Overall length of either set-up is 25 to 28 inches from top of funnel to tip of the extension - just long enough to reach the fill hole.
I also recommend using an adjustable, 'click'-type torque wrench because it's easier to manipulate. You won't have many degrees of rotation under the car.
You'll also need a way to get under the car such as a floor jack and jack stands (remember, SAFETY FIRST!
), as well as a pan or something to catch the oil. Make sure the pan clears the bottom of the car with the car down (not jacked-up). The reason becomes clear later.
Warm-up the engine. With the engine off, block the tires and jack-up the right side of the car. Get those jack stands under there for safety.
FINDING THE BOLTS.
From under the car, just on the inside of the right front tire under where the right axle comes out of the trans, look for the filler and drain bolts. They look completely different from the other assembly bolts. (Photo 3)
This photo shows the filler hole already unplugged and the filler extension on the funnel inserted.
Remove the filler hole bolt using a 17mm socket. You may need a breaker bar 'cause it's in there pretty tightly.
Insert the square socket drive on a 3/8 inch socket wrench directly into the drain plug (no socket required). The bolt was really stubborn so I again used a 1/2 inch breaker bar and a 3/8 inch reducer adapter. Get your drain pan under the drain hole. Unscrew the bolt and drain the trans.
While the trans is draining, lower the car to let as much trans fluid as possible drain out. Make sure your drain pan doesn't get crushed. Wait 5 minutes or so before raising the car again.
While the car is down, snake the funnel down through the engine compartment and towards the filler hole. (Photo 4)
With the car back up on jack stands, replace the drain bolt using a new washer. Tighten finger tight then torque to 29 ft-lb (4.0 kg-m).
. Reach over and insert the end of the funnel into the fill hole (see Photo 3 above). From the top of the engine compartment, pour in 2 qts of MT oil using the funnel. (Photo 5)
Let the oil drain through the funnel and into the trans for a couple of minutes. Pull out the funnel.
Reinstall the fill bolt with a new washer. Finger tight then torque to 33 ft-lb (4.5 kg-m).
Lower car and you're done. The 2 qts of oil is exactly the amount you need so you really don't need to check the level. Checking the trans fluid level is tough to do without a lift. The car must be level so if you raise the car with a jack, you will not get a true reading.
To check the MT fluid level:
With the car level, remove the fill bolt. Reach in with a finger and check if the trans fluid comes up just to the edge of the filler hole. (That's why the fill hole is so big.) Add more fluid if necessary.