1 hour ago, Eric Bloodaxe said:

I had my oil changed at 12 months but just looked out of interest and oil life is 44%, so I guess they didn't reset it. How does it actually work though - is it really analysing oil condition or just linked to time/mileage? 44% is just about where it should be on a time basis at just under 14 months out of 24 from first registration.

It won't be analysing the "oil condition", it will simply be using a calculation based on the mileage, time, type of driving to give the percentage. Not 100% sure on what to think of it as I think the "needs oil change" threshold is at just 5% which will for any standard user appear close to the 2 years anyway which imo is too long 

On the diesels it also takes into account the dpf regeneration frequency