Doesn't get any easier
I have changed my oil at least three times and it doesn't get any easier. I use a 6 inch adjustable wrench to remove the filter holder and yank the old filter out. I don't know why Opel chose a cartridge style filter. I suspect the bracing was probably added by Buick and is welded in place. I would be interesting to find out if the non US-spec models have the same bracing.