Sorry to hear about your Zafira fella. Must be really frustrating! It would have P****d me off TBH!
Personally i think its all about how well people look after their cars to how much oil they use. Before i joined this forum i used to get my auto coupe serviced once a year at Vx and that was it, but never missed a service. Bought my car with 50k on the clock and chain lasted to 117k. Now i pay a lot more attention to my car because just like most people i didnt realise that i need to look after it more often. Once the oil loses its circulation and starts clogging up, parts normally wear and thats when problems start. This would also show the oil taking ages to drain back into the sump etc.
Trouble is when these cars were new people just drove them. They probably didnt think about the long term damage.
As for you Zafira, If the overall condition of it is good then these cars do hold their value! I just bought a 2001 Zafira cheap, but the valuations were between £1800 - £2000 with 107000 miles. So you could get the engine done, have a few years of good motoring and then when you come to sell it you will still get a fair amount back.
Just my opinion but i hope it helps :thumbup: