Subaru ff-1/1300/1400/1600/1800/Brat 1970-1984 Repair Guide

Rear Drive Axle


The lubricant should be checked at regular intervals and changed at 60,000 mile (96,000km) intervals. When the vehicle is frequently operated under severe conditions, the lubricant should be changed at 30,000 mile (48,000km) intervals.


Use gear oil with API classification GL-5 for open differentials and GLS for limited slip differential. Viscosity should be:

SAE 90-above 30°F (-1°C)
SAE 85W-above 30°F (-1°C)
SAE 80W-below 0°F (-18°C)


Unlike the procedures outlined above, the lubricant level in the rear differential must be checked from underneath the vehicle. this procedure applies to four wheel drive models.

  1. Park the vehicle on a level surface. Block the wheels, place in gear, turn the engine OFF and engage the parking brake.
  3. Crawl under the vehicle from the rear until the differential housing can be reached easily.

Click image to see an enlarged view

Fig. Fig. 1 Rear drive axle drain and filler holes

  1. Remove the filler hole (upper) plug from the back of the differential case.
  3. If no lubricant trickles out carefully insert your finger (watch out for sharp threads) into the hole and check that the oil is up to the bottom edge of the filler hole.
  5. If not add the oil through the hole until the level is at the edge of the hole.
  7. Install the filler hole plug.