4RunnerSUV

Maintenance schedule

1. 1
   Every 5,000 miles or 6 months Full synthetic oil and filter change

   The VVT-i system depends on clean, low-viscosity oil to function properly. Toyota's 10,000-mile OCI recommendation assumes ideal conditions; the 4Runner's known VVT-i sludge and fitting issues make 5,000-mile intervals the smart choice in real-world driving — especially in Wisconsin winters with cold starts and short trips.

2. 2
   Every 30,000 miles Inspect and replace VVT-i oil line banjo fitting if showing any seepage

   This is the highest-risk failure point on the 5th-gen 4Runner. The aluminum fitting cracks slowly. Catching a small seep at a service visit costs a few hundred dollars. Catching it after it has dumped oil into the engine bay at highway speed may cost you the engine.

3. 3
   Every 30,000 miles Replace rear differential fluid (and front diff + transfer case on 4WD)

   Toyota's published interval is longer but upper Midwest conditions — seasonal temperature swings, water crossings, occasional off-road use — accelerate fluid degradation. Fresh fluid is cheap; rebuilt differentials are not.

4. 4
   Every 60,000 miles Replace spark plugs (iridium)

   The 1GR-FE uses iridium plugs with a long service life, but worn plugs on a 6-cylinder can cause misfires that look like VVT or sensor issues. Replacing on schedule eliminates them as a diagnostic variable.

5. 5
   Every 60,000 miles Inspect and flush brake fluid

   Brake fluid is hygroscopic — it absorbs moisture over time, lowering its boiling point. In Wisconsin winters where brakes work harder in cold and wet conditions, fresh fluid maintains consistent pedal feel and protects ABS components.

6. 6
   Every 90,000 miles or at first signs of seeping Inspect KDSS hydraulic lines (if equipped)

   KDSS-equipped trucks develop line seeps that worsen into leaks. Catching it at an early seep is a much smaller job than a full hydraulic system repair.

7. 7
   Annually (before winter) Test battery and load-test the charging system

   Cold-cranking amps drop significantly at sub-zero temperatures. The 4Runner's larger V6 needs a healthy battery to start reliably at -10°F to -15°F. Replace any battery showing reduced CCA before the first hard freeze.

8. 8
   Every 2 years or 30,000 miles Inspect and lubricate all underbody U-joints, driveshaft slip yokes, and 4WD hubs

   Road salt in Wisconsin accelerates corrosion on unlubed U-joints and slip yokes. The 4Runner's body-on-frame design exposes the front driveshaft and U-joints to significant salt spray. Grease them before they're needed — they won't give much warning before they fail.

Always defer to the manufacturer's service manual for warranty-mandated intervals.

Cost of ownership

The 4Runner is a low-drama ownership proposition. Annual maintenance on a well-kept example runs $600–$1,200 at an independent shop — mostly oil changes, filters, and fluid services. The big wildcard is deferred maintenance on a used purchase: if the VVT-i oil line, diff fluids, and spark plugs haven't been touched, budget $800–$1,500 upfront to bring it current. Fuel is the largest ongoing cost — this is not an efficient vehicle. But major unplanned repairs on a properly maintained 4Runner are genuinely infrequent, which makes the true cost of ownership competitive over a 10-year horizon.