There’ll be crevices and crannies, where stray bits of stuff collects and a flush process cleans them out
Which actually reminds me, most of these have and oil filter at the bottom underneath. it is the lowest point - not a filter so much as gauze (like a vw beetle).
Slipped my mind until now
If you tilt it slightly, you will see a nut head (about 16mm) cast onto a recessed body.
