Hi, Sorry for the delay but i come on here once or twice a day and while i do have a smart phone it's smarter than me! Yes, i was an MG/Rover technician and a Ford Master Tech before i left the dark side to work for an independent. I hav'nt used that Wynns stuff but it may be worth a try. I guess the first thing i'd check if it came into our place is the oil pressure, the tappets are among the last things in the oil supply so if it's low they will suffer and not pump up as well as they should. Is there a Vauxhall specialist as opposed to a dealer near you, if so it may be worth having a word with them first.