With no service records on the truck, I did a complete fluid service across every system. Fresh fluids are cheap insurance on a 200K+ mile drivetrain.
What I Serviced
- Engine oil — Drained and filled with Toyota-spec 5W-30
- Automatic transmission — Drain and fill (not flush) with Toyota Type IV ATF
- Transfer case — Drained and filled with 75W-90 gear oil
- Front differential — Drained and filled with 75W-90 GL-5
- Rear differential — Drained and filled with 75W-90 GL-5 with limited slip additive for the locker
The transmission fluid came out dark — definitely overdue. Everything else looked okay but better safe than sorry.