Changing differential oil

Differntial oil change intervalls

The owners and service manual recommends the following intervalls:

• Normal driving conditions: Every 48.000km / 30.000miles or 2 year (which ever comes first)
• Harsh driving conditions: Every 24.000km / 15.000miles or 1 year (which ever comes first)

Definition of harsh driving conditions

The service manual states the following definition:

• Less than 8km (5 miles) per trip on non-freezing weather conditions.
• Less than 16km (10m miles) per trip on freering temperatures.
• In hot weather climates with temperatures above 32°C/90°F.
• Extensive idling or long preiods of stop-and-go driving (e.g. as taxi or commercial deliver vehicle).
• Driving on mountainous roads.
• On muddy, dusty, or de-iced roads.
  

Additionally definition from other S2000 owners:

• Sport and fast paced driving with a lot of VTEC engagment.
• Long preiods of driving at 150km/h (93 mph) or above.
• Racetrack driving (most people recommend to change the oil after each racetrack visit).

Recommended differential oil

See: Differential_oil#Recommendations

Required tools and fluids

• 1L / 1qts differential oil (or a little more if you would like to "flush" the differential)
• New crush washer for the oil drain bolt (Honda #90401-PCZ-003)
• New crush washer for the oil filling bolt (Honda #90402-PCZ-003)
• 23mm socket or wrench (there is only limited space around the filling bolt)
• 24mm socket
• Ratchet
• Torque wrench (44Nm / 33 lb-ft)
• Oil catch pan
• Floor jack + 4 jack stands
• (Optional) A lube pump as it can be hard to fill the oil in the differential.

How to change the differential oil

Pre-conditions and jacking up the car

• Before your start it might be a good idea to drive the car for a while to increase the temperature of the oil in the differential.
• Put the car in the first gear and set the parking brake.
• Jack up the car on the front by using the central jacking point near the engine.
• There are two front-jacking-points on each side. Place one jack stand on each side at the jacking-point that is the furthest away from the front wheel.
• Lower and remove your floor jack and continue jacking up the rear by using the jacking point on the differential.
• Place your jack stands on the left and right side jacking points at the rear of the car.

Draining the oil

• The differential is located at the back of the car / at the end of the driveshaft and has two bolts (drain and filling).
• The bolt on the bottom of the differential is the drain bolt while the upper bolt on the drivers side is the filling bolt.
• Place your oil catch pan below the differential drain bolt .
• Remove the differential oil drain bolt with a 24mm socket from the differential.
• The old differential oil will now drain from the differential and you might need to re-adjust your oil catch pan.
• Next remove the differential oil filling bolt with a 23mm socket or wrench from the differential. You will notice that once the filling bolt is gone, more oil will come out of the differential oil drain.

• Once all the oil has be drained I like to fill fresh oil into the differential to "rinse or flush" the differential with the new oil.
• Wait until no oil (either old or new from "rinsing") comes out of the differential.

Adding new differential oil

• Replace the old crush washer from the differential oil drain bolt.
• Usually the crush washer will have to sides, one that has a rounded edge and one that has a sharper edge. The sharp edge should face the differential.
• Hand tighten the differential oil drain bolt. Then use your 24mm socket and a torque wrench and tighten it to 40Nm / 29 lb-ft.
• Fill in the transmission oil through the filling hole until the new transmission oil starts to leak out of the filling hole.
• This is the indicator that there is enough transmission oil in the transmission (usually 1.6L / 1,6qts).
• Replace the old crush washer from the transmission oil filling bolt.
• Usually the crush washer will have to sides, one that has a rounded edge and one that has a sharper edge. The sharp edge should face the transmission.
• Hand tighten the transmission oil filling bolt. Then use your 17mm socket and a torque wrench and tighten it to 44Nm / 33 lb-ft.

How to make sure no old differential oil is left in the differential

This gurantees almost 100% that no old transmission oil is left in your transmission and that it has been exchanged completely with new oil.
The same procedure is used by oil companies between test cycles in their R&D facilities.
You might want to do this when changing to a different type or brand of oil.

• Repeat the steps Changing_differential_oil#How_to_change_the_differential_oil three times and drive your car for a short time between each changing cycle.