Citroen DS oil filter o-rings

I don’t normally post about routine things such as oil changes, but in this case, there is an aspect to the oil change that is not obvious and is worth mentioning.

In general, the DS oil change is well covered on the Internet, as are the warnings to ensure the filter housing is properly aligned when inserted back into the sump.    The DS is an odd design, instead of a remote cartridge, the filter sits at the bottom of the oil pump and is accessible by removing a plate, and then a housing from the sump.      It is that housing that must align to the arrows or the engine will starve of oil.

However, there are two o-rings that should also be changed periodically.   This is mentioned in some of the forums but it was not really clear to me.

The diagram above shows the oil filter housing and the bottom part of the oil pump.    There is a big o-ring (35) that fits into a grove on the housing lower plate (14).   There is also a small o-ring (34), that sits under the plate that holds the filter in place.   These 0-rings do not come with a filter unlike on some cars, they must be purchased separately or as part of a kit from one of the parts suppliers.

I changed mine for the first time after doing about four oil changes since I got the car without having changed them.    They were very hard, so it is probably some years since they were done.