| Engine oil & filter | MB 229.5 synthetic on M112/M113 · G 500 (M113) ≈8.0 L (8.5 qt) with filter · M103/M104 confirm in manual | Now, then yearly | M112/M113 use a top-mounted cartridge filter (74 mm, 14-flute cap wrench). The listed filter fits the 1998-on V6 and V8 only.Mann oil filter kit HU 718/5 x (000 180 26 09) · FCP Euro ↗ |
| Air filter | M112/M113: paired elements · M103/M104 confirm in manual | Now | Hengst air filter set 273 094 04 04 (M112/M113) · FCP Euro ↗ |
| Spark plugs & wires | M112/M113: twin-plug heads (12 or 16 plugs), Bosch FR8DPP33 · M103/M104: 6 plugs confirm in manual | Now if no record | Oil in the plug wells points to valve-cover or (on the M104) head-gasket leaks.Bosch FR8DPP33 spark plug (M112/M113, single) · FCP Euro ↗ |
| Coolant & thermostat | MB 325.0-approved coolant, 50/50 with distilled water | Now | On an M104 G 320, watch for oil–coolant cross-contamination and the right-rear head seep.M112/M113 thermostat kit (Borg Warner) · FCP Euro ↗ |
| Automatic transmission | G 500: 722.6 5-speed, MB 236.14 ATF, ≈9 qt total · 4-speed (I6): ATF per its MB 236.x sheet confirm in manual | Now, then every 40,000–60,000 mi | On the 722.6, replace the 13-pin connector sleeve and set the level hot with the dipstick tool.FUCHS 722.6 ATF service kit (fluid, filter, gasket) · FCP Euro ↗FUCHS 722.6 13-pin connector service kit · FCP Euro ↗ |
| Transfer case | GL-4 gear oil · ≈3 qt (1997 G 320) — later cases may differ; check the tag confirm in manual | Now, then every 60,000 mi (MB interval quoted by owners) | Owners find these filled with diff oil by mistake. Fill on the front right, drain underneath, 14 mm hex. |
| Front & rear differentials | GL-5 hypoid gear oil (a 1997 G 320 owner used Red Line 75W-90) · front ≈1.4 L, rear ≈1.8 L (owner and AMSOIL figures) confirm in manual | Now | Loosen the fill plug before draining; drain plug to ≈60 Nm (owner figure). Test each lock afterwards.Red Line 75W-90 GL-5 gear oil (1 qt) · FCP Euro ↗ |
| Front knuckles, swivels & wheel bearings | Repack knuckles and bearings; grease the swivels; CV boots | Europa's interval: every 40,000 mi | One owner found local dealers didn't know the job — use a G specialist or the factory procedure with a dial indicator.Genuine Mercedes front wheel bearing, outer 009 981 48 05 — listed for 2002+ W463; confirm fit by VIN · FCP Euro ↗Genuine Mercedes front wheel seal 463 334 01 59 — listed for 2002+ W463; confirm fit by VIN · FCP Euro ↗ |
| Power steering fluid | MB power-steering fluid | Now | Febi power steering fluid (MB 000 989 88 03) · FCP Euro ↗ |
| Brake fluid & lock hydraulics | DOT 4 Plus (MB sheet 331.0) | Now, then every 2 years | The 1997 G 320 owner notes the locker circuit uses brake fluid — bleed it with the brakes.Genuine Mercedes DOT 4 Plus brake fluid, 1 L · FCP Euro ↗ |
| Drive belt, hoses & harmonic balancer check | Poly-V belt and tensioner; crank pulley | Replace belt now if age unknown | On the M112/M113, a wobbling or cracked balancer is a replace-now item.Corteco harmonic balancer / crank pulley 112 035 14 00 (M112/M113) · FCP Euro ↗ |
| Fuel filter | M112/M113: 002 477 30 01 · others confirm in manual | Now if no record | Mann fuel filter 002 477 30 01 (M112/M113) · FCP Euro ↗ |
| Vacuum system & lock test | Reservoir, hoses, switchover valves | Now | Tee in a gauge on each section; replace split connectors and perished rubber with vacuum-rated hose.Lisle 20300 vacuum gauge / pump tester · FCP Euro ↗ |