Whats the correct amount of oil for the CVH engine in Litre or ML.

I didn't check this out the other month and i've just started to have oil pressure light on.

New filter and oil poured in, once settled down in the sump the level was about 4mm above the max fill level.

I'm thinking of dropping it again and binning it and buying better oil as its Halfords own make. I did this oil change a couple of months ago and started engine up and run quite a few times so strange for the pressure light to stay off all this time.(I've checked to see if the plug is on the switch)