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Thats what I thought lol, spent two hours trying to get the 13mm sump plug off yesterday. Mum got her work hack (Calais) serviced at Barry Burke Holden last service and it just didn't want to come off. Took Bigjim, Capralicious and I 2 hours to get it off today. We threaded the 13mm plug so had to bash on a 12mm spanner! Then smack it with a hammer. Took ages but got it off. Put a new 15mm sump plug on as well. Moral of the story, don't get it serviced at Holden. Last time I did it on my SV6 took me less than 30min lol.