| Engine oil & filter(s) | 4.2 six: ≈8.2 L (one 1990 GQ DX owner's fill; engine type not stated). Grades quoted range from Gregory's 20W-40 to 15W-40 diesel oil confirm in manual | Change now, then at short intervals for an old diesel confirm in manual | The TD42 uses two spin-on filters. HD Automotive's listing for the Ryco Z115 says two are required. TB42, RD28 and RB30 each take their own filter.Genuine Nissan oil filter, TD42 (GQ/GU/Maverick) · Patrolapart ↗Ryco Z115 oil filter, GQ TD42 (two required) · HD Automotive ↗Genuine Nissan oil filter, GQ TB42 · Patrolapart ↗Genuine Nissan oil filter, GQ/GU RD28 · Patrolapart ↗ |
| Air filter | Engine-specific element: oval for TB42 (and GU TD42 NA), cylindrical for RD28, separate EFI element for TB42E | Inspect every service; replace when dirty, sooner on dusty roads | Check the airbox seals and the snorkel joints too. A dusty diesel intake is how TD42s die young.Genuine Nissan oval air filter, GQ TB42 / GU TD42 NA · Patrolapart ↗Genuine Nissan cylindrical air filter, GQ RD28 · Patrolapart ↗Genuine Nissan air filter, GQ TB42E EFI · Patrolapart ↗ |
| Fuel filter | Diesel: engine-bay filter on the driver's side (TD42/RD28). EFI petrol: in-line filter under the bonnet | Replace now confirm interval in manual | Imported trucks may have sat for years. Drain water from the diesel filter and bleed the system afterward.Genuine Nissan fuel filter, GQ/GU TD42 / RD28 diesel · Patrolapart ↗Genuine Nissan fuel filter, GQ TB42E / GU TB48 · Patrolapart ↗ |
| Valve clearances (TD42 tappets) | One forum member sets 0.35 mm at ambient temperature confirm intake/exhaust in manual | A forum member suggests about every 20,000 km | TDC on cylinder 1: adjust valves 1, 2, 4, 5, 8, 9. TDC on cylinder 6: adjust 3, 6, 7, 10, 11, 12. Fit a new rocker-cover gasket.Rocker cover gasket kit, TD42 · Patrolapart ↗ |
| Glow plugs (diesel) / spark plugs (petrol) | TD42: genuine single-pole glow plugs. RD28: its own plugs. TB42: genuine plug set | Test glow plugs now; replace spark plugs now on petrol trucks | A slow cold start on a diesel is usually glow plugs or the glow-plug relay before it's anything worse.Genuine glow plug, TD42/TD42T/TD42Ti · Patrolapart ↗Genuine Nissan spark plug set, TB42/TB45 · Patrolapart ↗ |
| Timing belt (RD28T and RB30 only) | Belt, tensioner and idler kit; TD42 and TB42 have gear-driven cams and no belt | Now if there are no receipts; ExplorOz owners report about 100,000 km confirm in manual | Replace the crank and cam seals while you're in there, and consider a new balancer bolt.Timing belt kit, RD28 · Patrolapart ↗Timing belt kit, RB30 · Patrolapart ↗ |
| Coolant, thermostat, hoses & belts | TD42 thermostat: genuine 76°C, part 21200-58G04 · coolant type confirm in manual | Flush and refill now; hoses if they're original or soft | Overheating is the GQ's signature failure, and on automatics the transmission cooler is inside the radiator. Pressure-test the system and check the fan clutch.Genuine TD42 76° thermostat 21200-58G04 · HD Automotive ↗Gates radiator hose set, GQ TD42 · HD Automotive ↗Gates fan belt kit, GQ TD42 with A/C · HD Automotive ↗ |
| Manual gearbox | 75W-90 GL-4 · ≈3.9 L (Gregory's, quoted by owners) | Change now | Owners describe the big gearbox behind the 4.2-litre engines as very strong; listen for whine and check the shifter boot for splits that let in water.Genuine Nissan diff/gearbox/transfer fill plug, GQ/GU · Patrolapart ↗ |
| Automatic transmission (RE4R03A) | ATF per manual confirm in manual | Drain-and-fill now if there's no record | Rebuilds reportedly cost around A$3,000. Fix any cooling problems first, because the trans cooler is inside the radiator, and check the cooler lines for leaks. |
| Transfer case | 75W-90 GL-4 · ≈2.0–2.2 L (owner figures) | Change now | The front diff, gearbox and transfer case share one breather in the passenger guard. Make sure it isn't blocked.4-point diff/transmission breather kit, GQ/GU · Patrolapart ↗ |
| Front differential | 80W-90 GL-5 (Gregory's) · ≈5–5.4 L (owner figures) | Change now, and after deep water crossings | If the front diff has been losing oil, check the swivels: a failed inner axle seal pushes diff oil into the grease-filled swivel hub. |
| Rear differential (LSD) | LSD-rated gear oil; owners use 85W-140 LS · ≈2.5–3.0 L | Change now | Most GQs have a rear LSD. Use limited-slip oil or add a friction modifier if it chatters in corners. The stock rear breather vents near the fuel tank, so extend it.Diff centre gasket, H233 (GQ/GU) · Patrolapart ↗ |
| Swivel hubs & front wheel bearings | Grease-lubricated CV and swivel bearings; kingpin preload set with shims | Inspect now; repack and reseal if there's any oil or play | Repack the wheel bearings with high-temperature grease. Greasy gunk on the swivel balls usually means a leaking inner axle seal, not a swivel seal.Swivel hub wiper seal kit, GQ Y60 · Patrolapart ↗Ultima front wheel bearing kit, GQ · HD Automotive ↗ |
| Brake fluid, pads & hoses | Fluid type per the cap/manual confirm in manual; twin-piston front calipers on EFI TB42E trucks, single-piston on non-EFI ones (per Patrolapart pad listings) | Flush now | If the truck has been lifted, check that the brake lines were lengthened and the rear proportioning valve was adjusted.Genuine Nissan rear brake pads, GQ · Patrolapart ↗Bendix front pads, GQ twin-piston (DB1257) · HD Automotive ↗ |