Unimog Maintenance Guide: Engine Oil Change (Checklist & Torque Specs)

Quick Reference: Tools & Parts

OIL

Shell Rotella T4 – 15w40 (Capacity of Engine + filters: 17.5 Litres (4.62 gallon))

COMPONENTS

1x Copper crush gasket (26mmx32mm)
2x Copper crush gasket (10mmx14mmx1.0)
2x Oil Filter – MANN HU 932/4x

TOOLS

Oil pan drain plug: 14mm Allen Key / Hex socket
Canister drain Plugs: 14mm Socket
Canister to housing bolts: 19mm Socket

TORQUE SPECS

Oil Pan Drain Plug: 50+10NM(37-44 ft. lbs.)
Canister Drain Plugs: 15+2NM(9.5 – 12.5 ft. lbs.

WARNING: My Unimog is a model 435.117 with an OM352A engine model: 353.959. All technical details pertain to that engine and that engine only! Do the research into your own engine and it’s particular needs. Also, there is a very possible chance I am wrong about anything and everything. I am not a professional. This information is for entertainment purposes only.

Exploded diagram-like photo of actual engine oil filters, canisters, and parts.

Changing the engine oil on a Unimog (like the 435/U1300L) isn’t difficult, but (in my case) it is messy and requires specific torque specs to avoid ruining your oil pan. This guide covers the step-by-step process, the specific MANN filters you’ll need, and the ‘Double O-Ring’ mistake that I made.

Draining the Unimog Engine Oil

  1. Run engine for a few minutes to warm up oil
  2. Remove oil drain plug (M26x1.5 / 14mm hex) – located bottom of oil pan. Let oil drain. Use 2x 5 Gallon buckets.
  3. Remove canister drain plugs (M12x1.0 / 14mm socket) from both oil filter housings. Let oil drain.
  4. Remove oil filter canister to housing bolts (M12 long bolt / 19mm socket) and canister with filter in it.
  5. Remove both filters and rubber O-rings from top of canisters and discard
  6. Clean canisters
  7. Make sure all old O-rings and crush washers have been removed and are accounted for

Refilling and Torque Specs

  1. Replace oil pan drain plug (M26x1.5 / 14mm hex)
    Washer: New brass crush washer (26mmx32mm)
    Torque: 50+10NM(37-44 ft. lbs.)
  2. Replace canister drain plugs (M12x1.0 / 14mm socket)
    Washer: New brass crush washer (10mmx14mmx1.0)
    Torque: 15+2NM(9.5 – 12.5 ft. lbs. This seemed like too much. Maybe just lightly tighten by feel.)
  3. Insert new Filters (MANN HU 932/4x) into canisters
  4. Insert new O-rings in top channel of canisters
  5. Put the oil filter canister to housing bolts (M12 long bolt / 19mm socket) into the canisters
    Washer: There is no washer
    Torque: 40-45NM(30-33 ft. lbs.)
  6. Fill each oil filter canister with oil up to near the top (1.5 Litres(1.6 Quarts) each filter)
  7. Mount canisters and tighten
  8. Fill engine with oil – Shell Rotella T4 15W-40 (14.5 Litres/(3.83 gallon))
  9. Check dipstick level (IMPORTANT! I actually overfilled the engine by half a gallon. I incorrectly thought my jugs were 2 gal – they were 2.5 gal. This step saved me.)
  10. Run engine for a few minutes
  11. Check dip stick and adjust level if needed.

Source: Mercedes-Benz Unimog 435 Workshop Manual, Volume 1, Group 18.8 (Engine Lubrication), Section 1.2 (Tightening Torques).

Exploded vie diagram of oil filter assemblies from Mercedes
Workshop manual list of tightening torques

Unimog Oil Filter Assembly (MANN HU 932/4x)

Here is the filter I use and the included items:

  1. The big O-ring – goes on the canister
  2. The big brass washer – This fits the big oil pan drain plug. (26mmx32mm)
  3. The tiny aluminium washer – fits the drain plug for each canister (10mmx14mmx1.0)
Photo of all included pieces in filter box

Beware: Double O-ring situation

This is why I included step #7 in “Draining” checklist. When changing the oil the first time, I didn’t notice that the old O-ring stuck to the filter housing on the engine. So, I ended up with two O-rings which were found by the mechanic at Terry Lee Enterprises in Colorado.

We had driven from Long Beach to Flagstaff on one trip and Long Beach to (almost) Colorado Springs on the trip to Terry Lee, with this O-ring situation. Luckily it didn’t leak. Or… more likely, it didn’t leak enough to cause a problem. You can see the black streaks running down the sides. Those definitely weren’t there when I did the oil change.

Always reach your finger up into the filter housing to feel for the old rubber seal. If it’s stuck there and you stack a second one on top, it could (and probably will) leak under pressure.

Photo of my double o-rings from Terry Lee Enterprises

Parts list – Engine Oil Change

ComponentPart NumberCostQuantitySource
Shell Rotella T4 – 15w40 (1.)–$15.00/gal17.5 Litres (4.62 gallon)Amazon
Filter – MANN HU 932/4x (2.)–$14.902Expedition Imports
Copper crush gasket 26mmx32mm–$1.551Belmetric
Copper crush gasket 10mmx14mmx1.0–$0.282Belmetric

1. Where possible, sourcing is directed to specialized suppliers. Amazon links are provided only for general availability and convenience.

2. Please, please, please research the part numbers for YOUR Unimog. They are probably different than mine.

Leave a Reply

Related Posts