To be honest there is nothing wrong with halfords own brand stuff. The kit at work we use shell rimula on the HGV's and I think it's mobil in the merc sprinters. All had no problems really
If they say 4.3litres don't just put it 4.3, always put less in first and keep checking the dipstick as you fill it up from there bit by bit. We had it with the DAF's when we first got them. They said 37 litres, so that's what we did. They kept alarming on the dash with high oil level. There will always be a little old oil left in the sump