Changing engine oil is usually an straight forward procedure on most cars, however the location of the oil filter housing for the inline six cylinder M110 engine, makes the job a bit more messy and annoying than necessary. Now these cars with M110 engines are starting to get pretty old, which means more often oil changes with the increased mileage. My 280CE is of now 38 years old and I do regular oil changes at every 5000 km. This might seem often, but the little amount of actual kilometres this car is seeing it is usually only once per year.
If the car is parked for long periods, moisture will build up inside the block and the oil will eventually turn milky white, which can be noticed if opening the oil filler cap. If you are doing the oil change yourself, you will get a clear indication of the health of the engine. This you won’t get at a workshop unless it is a special workshop for classic cars. Who can afford that anyway?
This is an article long overdue, but since I did a lot of work on the W123 laterly the opportunity presented itself. Also got inspired by writing this since I already had an article on changing oil in the big brother M120 engine: https://mercbenz123.com/posts/engine-oil-change-m120-engine-w140-s-class/
More articles on W123 coming up soon too!
Preparation
You will need a few supplies and tools before starting on the job. Also it is best to change the oil when the engine is warm since this will let the oil drain easier. So make sure you take a short spin just before changing the oil. Changing the oil can be done in any season, so no need to wait until summer for this one. Just do it!
Supplies
- 6.5L Synthetic Motor oil with viscosity for your climate and use: A good all-rounder could be 10w-40.
- Good quality oil filter. I recommend getting a filter from Mann, since it will come with all new washers and gaskets. https://www.mann-filter.com/en.html
- Paper towels or rags to clean up oil
- Brake cleaner
Tools
- Torque wrench
- Sockets
- Oil drip pan
- Ramps or jack stands
Procedure
Make sure the engine is warm and drive the car upon ramps or raise the front of the car upon jack stands. The car is usually high enough just by itself to drain the oil without raising it up, but in order to reach under to the oil filter, you need the space to crawl under it.
Draining the old oil
Normally you would open the oil filter can before draining the oil, but since this will literally spilling oil everywhere, you must drain the oil pan first. Open the oil filler cap to let the oil drain out easier. So grab your cleaned oil drip pan, or dirty if you do not care for inspecting the oil afterwards. It is your call. Grab your trusty 13mm socket and crank open the oil drip plug.
When the oil have stopped dripping, you can move over to removing the oil filter housing. If you have never seen it, it is a large aluminium canister located underneath the left side on the engine towards the back. See image below:
The oil filter is held in place with a single bolt, but be prepared for oil splashing when you start removing it, try balancing the filter into the upright position since it will be completely full with oil. So be prepared to get oil everywhere and keep you mouth closed. After the oil housing is removed, clean the mating surface and the area around.
Replacing oil filter and washers
Pour out the old oil in the filter housing and notice the orientation of the old filter and washers. Take out the oil filter and throw it away. Now clean out the old gunky oil from the oil filter housing. Use some break cleaner and get all that gunk out and dry clean.
Hopefully your new filter has some new washers in the pack. Replace the lower washer on the oil filter bolt which goes on the outside of the filter housing (this not a copper washer). There is a spring and a spring retainer inside the housing below the filter, keep this in the same orientation before inserting the new filter. Place the new filter with the narrow hole down and the larger hole upwards. The side for up usually has a little handle on it. Do not forget to replace the new rubber gasket around the edge of the filter housing.
If you notice in the oil filter kit that there is an additional large copper washer there with an unusual shape. This washer is for the large bolt which holds the oil pressure relief valve right next to the oil filter housing. However this only needs replacing if you see oil seepage from the area. No need to replace this every oil Change. The torque for this bolt is 41 Nm.
Before reinstalling the oil filter, make sure you top up the oil filter completely with new oil. This will reduce the wear at the first startup after the oil change since more oil will be available for circulation right away. This is not possible in all engines, but here there is an opportunity in the M110 engine.
Reinstall the oil filter carefully not trying to spill out the oil from the new filter. Hand tighten so you can feel you do not ruin the threads. To tighten you will need to use a torque wrench and torque it to 35 Nm. This is pretty tight and will prevent leakage through the housing.. Too tight however and you will ruin the filter housing. Use a rag to clean up the filter housing and area completely so you can inspect for oil leaks later.
Adding new oil
Before pouting in the new oil, you can inspect the old oil and see if there is any residue and metal parts at the bottom of the drip pan. My oil looked alright, not any metal particles or excessive old oil, but because the car have been sitting for so long with only short starts now and then, the oil pan had built up some gunk which came out when draining the oil. Nothing serious, but it was a good time to replace the oil for sure.
Then at last replace the copper washer on the oil drain plug bolt and torque it to 41 Nm. Very important to put this plug back before you pour in the new oil. The engine takes 6.5 L of oil, but do not pour in all at once, pour in around 5.5-6 L and start measuring, otherwise you will overfill and have to suck up the extra oil. There is always some old oil taking up some capacity. Remember to use a funnel to avoid unnecessary spills.
When the oil level is up to the minimum mark on the dipstick, pour another 100 ml between each measurement until you are between the minimum and the maximum mark. The correct oil level measurement is only made when the engine is turned off!
Now you can start up the car an let it idle for a few minutes, and while the engine is running, go under the car and check for oil leaks. Inspect the oil filter if it is leaking and the oil drip plug. If everything looks fine, you can lower the car and take it for a short spin.
Go on a short drive just to get the engine up to operating temperature and head back home. Now shut off the engine and re-measure the oil level. If it is between the minimum and the maximum mark, the oil level is good. If the oil level is still under minimum, then add some oil to get it back to the right level. However if the level is above the maximum, you should suck out some of the excessive oil. This might be unnecessary if the level is just slightly above maximum (a few mm), since there is a natural oil usage from the M110 engine and the level will be fine soon anyway.
So DIY you next oil change and become confident in fixing your own cars!
Cheers, Robs out!