| Engine oil & filter | API SJ/SL 'Energy-Conserving' or ILSAC multigrade · SAE 5W-30 preferred · 5.2 L (5.5 US qt) with filter (Toyota owner's manual) | Then every 5,000 mi or per the owner's manual | Spin-on filter on the 5VZ-FE. Check for valve-cover seepage while you're there (see repairs).Oil filters for the 3.4 V6 · RockAuto ↗ |
| Engine air filter | Panel filter in the airbox | Inspect at every oil change; replace when dirty | Dusty-trail trucks clog these fast.Engine air filters · RockAuto ↗ |
| Cabin air filter (add-on) | None from the factory | Optional add-on | AdventureTaco notes the 3rd gen 4Runner never had a cabin filter; their kit fits in the blower-motor housing under the glovebox (three T25/8 mm screws).AdventureTaco in-cabin air filter kit (3rd gen 4Runner) · AdventureTaco ↗ |
| Spark plugs | Denso K16TR11 (Toyota 90919-01192) or NGK BKR5EKB-11 · gap 1.1 mm (0.043 in) (Toyota 2001–02 owner's manuals; Toyota-Club plug table) | Replace now if history unknown | Six plugs; Toyota-Club lists the same plug for the 5VZ-FE in the 1999–2003 Tundra and the Hilux Surf.Spark plug, Denso K16TR11 (Toyota 90919-01192) · ToyotaPartsDeal (Toyota OEM) ↗Spark plugs (other brands) · RockAuto ↗ |
| Timing belt, water pump & thermostat | Belt 13568-69095 · Aisin pump · 82 °C thermostat 90916-03075 | Every ≈90,000 mi (or now, if undocumented) | Do the pump, idlers, hydraulic tensioner, cam/crank seals and thermostat with the belt — AdventureTaco's OEM kit list. See the repair card above for the procedure.Timing belt (Toyota 13568-69095) · ToyotaPartsDeal (Toyota OEM) ↗Thermostat, 82 °C (Toyota 90916-03075) · ToyotaPartsDeal (Toyota OEM) ↗Timing belt & component kits · RockAuto ↗ |
| Coolant | Toyota red Long Life Coolant (00272-1LLAC concentrate, mixed with distilled water) · 8.0 L (9.0 L with rear heater) | Drain and refill now; renew with every timing belt | AdventureTaco refilled with two gallons of red concentrate plus distilled water after the belt job. Don't mix in green conventional coolant.Toyota Long Life Coolant, red concentrate (Toyota 00272-1LLAC) · ToyotaPartsDeal (Toyota OEM) ↗ |
| Drive belts | A/C 99364-20870 · alternator 90080-91090 · power steering 90080-91126 | Replace with the timing belt | All three come off for the timing job anyway; part numbers from AdventureTaco's OEM kit.Drive belts · RockAuto ↗ |
| Automatic / manual transmission | Automatic: ATF Dexron II/III · ≈2.0 L per drain and refill (4WD). Manual: 75W-90 GL-4/5 · 2.2 L | Drain and refill now, then per the owner's manual | A drain and refill replaces only part of the automatic's fluid, so on a truck with unknown history repeat it two or three times over a few hundred miles rather than one high-pressure flush.Automatic transmission fluid · RockAuto ↗ |
| Transfer case | 75W-90 GL-4/5 · 1.0 L (lever control) / 1.2 L (lever + button control) | Change now, then with the diffs | Crack the fill plug before you drain.Transfer case fluid · RockAuto ↗ |
| Front & rear differentials + rear breather | Hypoid GL-5 · front 1.15 L: owner's manual gives SAE 75W-90 for A.D.D. trucks, Toyota-Club lists 80W-90 · rear 2.45 L (no locker) / 2.75 L (with locker): SAE 90 above −18 °C, SAE 80W or 80W-90 below (owner's manual) | Change now; after any deep water crossing | The rear axle's breather sits on the housing and can suck in water when a hot diff is submerged. AdventureTaco's fix: a union plus hose run up to a breather plug behind the fuel door.Gear oil · RockAuto ↗Breather plug (Toyota 90930-03136) · ToyotaPartsDeal (Toyota OEM) ↗Breather union (Toyota 90404-51319) · ToyotaPartsDeal (Toyota OEM) ↗ |
| Power steering fluid | ATF Dexron II/III | Check; turkey-baster refresh if dark | Same fluid as the automatic transmission.Power steering fluid · RockAuto ↗ |
| Brake fluid | DOT 3 or DOT 4 | Flush now if history unknown, then per the owner's manual | Rear drums: inspect for gear oil on the shoes (see rear axle seals).Brake fluid · RockAuto ↗ |
| Fuel filter | Toyota 23300-62030 (4Runner-specific bracket; Tacoma's differs) | With the timing belt (≈90,000 mi); every 30,000 mi in very dusty country | Frame-mounted; 14 mm flare-nut wrench plus a 19 mm to hold the filter. AdventureTaco skips the FSM's fuel-pump-disconnect step and catches the spill.Fuel filter (Toyota 23300-62030) · ToyotaPartsDeal (Toyota OEM) ↗ |
| PCV valve & grommet | Valve 12204-62010 · grommet 90480-18001 · hose 12261-62041 (optional) | Replace now (cheap, 30 minutes) | Old grommets harden and crumble into the engine on removal — pick out every piece.PCV valve (Toyota 12204-62010) · ToyotaPartsDeal (Toyota OEM) ↗PCV grommet (Toyota 90480-18001) · ToyotaPartsDeal (Toyota OEM) ↗ |