| Engine oil & filter | MB 229.5 (e.g. 5W-40) · 9.0 L (2.4 US gal) with filter. That's the same for the M273 (2013 and 2014 operator's manuals) and the M176 (2016 and 2018 manuals; the 2016 manual also accepts MB 229.3) | Now, then per the service indicator. Mercedes' 2013 US booklet sets it at every 10,000 mi or 1 year | Both engines use a cartridge filter in a housing on top of the engine — replace the cap O-ring and drain-plug washer every time. FCP Euro also sells a 229.52 kit for the M176, but the operator's manuals list 229.5.Liqui Moly 5W-40 (MB 229.5) oil change kit, 9 L, with filter — M273 · FCP Euro ↗Liqui Moly Top Tec 0W-30 (MB 229.52) oil change kit, 9 L — listed for G 550 / G 550 4×4² · FCP Euro ↗ |
| Air filters | M273: two filter elements in the air box | Now if undated. Mercedes: every 40,000 mi or 4 years for the M273 (2013 US booklet); every 40,000 km or 2 years for the M176 (Canadian 2016 booklet); sooner in dust | FCP Euro notes the M273 air box holds two filters — replace both together. Dusty trail use shortens the interval.Air filter set 273 094 04 04 (M273, pair) · FCP Euro ↗Genuine Mercedes air filter set 177 094 00 04 (M176, 2016–2021) · FCP Euro ↗ |
| Cabin air filter | W463 cabin filter | Now, then yearly | Cheap, and an old one makes the climate control work harder.Mahle LAK120 cabin air filter · FCP Euro ↗ |
| Spark plugs & coils | M273 and M176 spark plugs (Mercedes-spec) | Now if no record. Mercedes: every 60,000 mi or 6 years for the M273 (2013 US booklet); every 100,000 km or 5 years for the M176 (Canadian 2016 booklet) | FCP Euro suggests doing M273 plugs alongside the oxygen sensors (≈100,000 mi). Check misfire counters before buying coils.Bosch spark plug kit (M273) · FCP Euro ↗Genuine Mercedes ignition coil 272 906 00 60 (M273) · FCP Euro ↗Genuine Mercedes spark plug 000 159 05 00 (M176) · FCP Euro ↗Genuine Mercedes ignition coil 177 906 02 06 (M176) · FCP Euro ↗ |
| Coolant & thermostat | M273: Genuine Mercedes or Pentofrost NF · 2015-on: MB 325.6 listed by FCP Euro · 50/50 with distilled water | Coolant now if undated; M273 thermostat at 60,000 mi | FCP Euro recommends replacing the M273’s map-controlled thermostat at 60,000 miles — it’s the engine’s most common failure.Genuine Mercedes coolant, MB 325.6 (pink), 1 gal · FCP Euro ↗BorgWarner thermostat kit 272 200 05 15 (M273) · FCP Euro ↗ |
| Automatic transmission (7G-TRONIC 722.9) | MB 236.14 for gearboxes built before June 2010 · MB 236.15 (blue) from 21 June 2010 on | Now if no record. Mercedes: oil and filter every 40,000 mi or 4 years on the M273 G 550 (2013 US booklet); every 120,000 km on the 2016 (Canadian booklet) | No dipstick: drain the pan, fit a new filter and gasket, then set the level at temperature with a scan tool. A drain-and-fill only swaps part of the fluid — a second change soon after improves the ratio. Check the build date before buying fluid.Genuine Mercedes ATF, MB 236.15 (blue) · FCP Euro ↗Genuine Mercedes ATF, MB 236.14 (722.9 built before June 2010) · FCP Euro ↗Febi 722.9 transmission filter kit · FCP Euro ↗ |
| Transfer case | Gear oil, not ATF, if your truck has the VG 150 E case: Mercedes' WIS fluid table, as reproduced for a 2011 G 55 (W463), lists SAE 80, 80W or 80W-85 for it (SAE 90 or 85W-90 in hot climates) · capacity confirm in manual | Now if no record. Mercedes: every 50,000 mi or 5 years (2013 US booklet); every 120,000 km (Canadian 2016 booklet) | Two-speed, 50:50 case with the centre lock. Check for weeps at the input and output seals while you’re underneath. |
| Front & rear differentials | Hypoid gear oil. FCP Euro lists 75W-90 GL-5 for 2009–2014 G 550s, and the WIS table (approval sheet 235.0) allows 75W-90, 80W-90, 85W-90 or 90 for hypoid axles · capacities confirm in manual | Now if no record. Mercedes: every 50,000 mi or 5 years (2013 US booklet); every 80,000 km or 4 years (Canadian 2016 booklet) | Both axles carry 100% lockers. Look for gear oil on the inner front wheels and brakes — the front axle seals are a known leak point.Red Line 75W-90 GL-5 gear oil (listed for 2009–2014 G 550) · FCP Euro ↗ |
| Diff locks & vacuum lines | Inspection — engage centre, rear, front in order | Now, then monthly exercise | Disuse is what kills lockers, and Mercedes' service booklets have you engage them at every service. The locking mechanism has its own reservoir filled with brake fluid, which is changed with the brakes (2013 US and 2016 Canadian booklets). If one won't engage, check the fluid level and look for a split vacuum line or connector before suspecting the differential.Genuine Mercedes vacuum hose 007 997 61 82 · FCP Euro ↗Genuine Mercedes vacuum hose connector 117 078 03 81 · FCP Euro ↗ |
| Power steering fluid | MB 236.3 power steering fluid (recirculating-ball box) | Now if dark or no record. Mercedes' 2013 US booklet only checks the level at service and gives no replacement interval | Never mix with ATF. A turkey-baster swap of the reservoir, repeated a few times, refreshes most of it.Febi 08972 power steering fluid, MB 236.3 · FCP Euro ↗ |
| Brake fluid | DOT 4 Plus (MB 331.0) · also fills the diff-lock mechanism | Now, then every 2 years / 20,000 mi (2013 US booklet). The Canadian 2016 booklet says every year | Brake fluid absorbs water. A heavy truck that tows or descends trails needs a fresh, high-boiling-point fluid.Genuine Mercedes DOT 4 Plus brake fluid, 1 L · FCP Euro ↗ |
| Drive belt, tensioner & idlers | M273: belt + tensioner + idlers · M176: belt | M273 tensioner & idlers every 60,000 mi | FCP Euro recommends replacing M273 belt tensioners and idler pulleys every 60,000 miles; check for oil on the belt from the oil-cooler seals.FCP Euro drive belt kit — belt, tensioner, idlers (M272/M273) · FCP Euro ↗Continental accessory drive belt (M176) · FCP Euro ↗ |
| M273 oil-leak inspection | Breather cover, oil-cooler seals, cam-magnet connectors | At purchase | Unplug each cam-magnet connector and look for oil — caught early it’s a cheap fix; left alone, oil wicks toward the engine control unit.Camshaft adjuster magnet repair kit (OE supplier) · FCP Euro ↗ |
| Steering damper & battery | Steering damper · group 49 AGM battery | At purchase | A tired damper causes highway wander and shake. Load-test the battery.Stabilus steering damper 463 463 00 32 · FCP Euro ↗Bosch S6 AGM battery, group 49 · FCP Euro ↗ |