Procedure
- Golden rule: crack the FILL plug loose FIRST on both the gearbox and diff. Draining a box you can't refill is a tow-truck story.
- Warm fluid drains faster and dirtier - a short drive first helps.
- Gearbox: drain plug out, let it finish dripping, inspect the magnetic plug. Fine paste is normal wear; glitter chunks are a conversation with a transmission shop.
- Refill through the fill hole with the pump until fluid dribbles back out the fill hole at level - that IS the full mark. New crush washer on both plugs.
- Rear diff: same ritual. The R160/R180 holds barely a quart and works hard - it deserves fresh fluid every couple of years.
- Manual boxes that shift notchy cold often improve dramatically with a quality GL-5; some 6MT owners prefer specific friction-modified fluids - check what your box likes.
- Torque plugs to spec, wipe everything, and check for drips after the next drive. Log the date and mileage - future you forgets.
Work at your own risk. Torque values and procedures vary by vehicle — always confirm against the factory service manual for your exact model.