On all models of the Metro and Rover 100 there are parts of the suspension that pivot. On the back is where the radius arm is connected to the sub frame. There are a small grease nipple at the end of the pivot shaft. Surrounding this pivot shaft are bearings. It is these bearings which need regular greasing. From memory it should be minimum of every 3 months.
What if my grease nipple becomes blocked by road dirt?
The nipple itself is screwed into the end of the pivot shaft and can be removed with a 8mm socket. I recomend using a 6 sided socket only to avoid rounding the sides off. It may also be worth cleaning the road dirt around nipple off to get the socket to fit full flush onto the grease nipple for removal. Then simple push through a small screw driver or anything else to clear the middle and refit. Do not be tempted to push into a blocked nipple in place as this will push road dirt onto the bearings which will vastly increase wear.
Location of rear greasing point
Location of front greasing point
Grease gun connected
Why does it need grease?
The radius arm central pivot or shaft is surrounded by bearings. The radius arm moves up and down constantly when the car is moving. As its a moving part there are bearings inside and these need to have grease at all times to avoid increased wear to the bearings and pivot shaft.
The picture below shows a new radius arm with the pivot shaft removed exposing the long bearings inside that surround the shaft.
The picture below shows the old pivot shaft removed covered in old dirty grease. Under the grease are many wear marks some a couple millimetres deep which will give play and movement in the radius arm leading to an eventual MOT fail.