ExplorerSUV

Maintenance schedule

1. 1
   Every 5,000 miles or 6 months — do not rely on the original 7,500-mile schedule on a high-mileage 4.0L Engine oil change (5W-20 full synthetic recommended)

   The 4.0L SOHC timing chain and VCT solenoids are extremely sensitive to dirty oil. Sludge buildup is the #1 cause of the expensive timing chain failures on these engines.

2. 2
   Every 30,000 miles or immediately if unknown Transfer case fluid change

   Almost never done by prior owners. Fresh Mercon LV fluid prevents the internal wear that kills the BorgWarner transfer case. This is cheap insurance on a $900–$1,800 repair.

3. 3
   Every 30,000–40,000 miles Transmission fluid and filter service

   The 5R55S does not have a lifetime fluid — it needs regular changes to maintain shift quality and prevent early failure.

4. 4
   Every 50,000 miles or 5 years Coolant system flush and inspection

   Inspect plastic thermostat housing and intake manifold area for leaks at each flush. Degraded coolant causes internal corrosion and accelerates plastic part failure.

5. 5
   Every 60,000 miles Spark plugs (4.0L V6: Motorcraft Platinums)

   Neglected plugs cause misfires and stress on coil packs. On the 4.0L, rear plugs are harder to access — do them on schedule to avoid a harder job later.

6. 6
   Every 2 years Brake fluid flush

   Four-wheel disc brakes absorb moisture in the fluid over time. Fresh fluid prevents internal caliper and ABS modulator corrosion — critical for Wisconsin winter stops.

7. 7
   Monthly through winter, thorough inspection each spring Undercarriage wash and inspection

   Road salt is relentless on frame, brake lines, fuel lines, and floor pan. Catching rust early saves major repair costs. Spray exposed metal with a corrosion inhibitor each fall.

8. 8
   Every fall before temperatures drop below freezing Battery load test

   A battery that tests marginal in September will likely fail to start the Explorer at -10°F in January. At 18+ years old, most original batteries are long gone — verify the current one is up to spec.

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

Cost of ownership

A well-maintained 2006 Explorer with the 4.6L V8 can be a relatively affordable SUV to own day-to-day. The risk is the 4.0L V6 timing chain job, which can run $1,200–$2,800 and hits without warning on neglected examples. Budget for a transfer case fluid service, transmission service, and a thorough undercarriage rust inspection as immediate priorities on any used purchase. Fuel economy is the ongoing soft cost — this is not a frugal vehicle.