Been running my Skoda Fabia 1.6TDi on B50 for some time. Started in 2017 with about B20 then gradually worked it up to B50. Done about 40,000 miles on B50. Still got a working DPF that regenerates OK at B50, but going up from there it doesn't seem to regenerate so well. I monitor the dpf with an Android app called VAG DPF. Had a recent problem with the tank fuel pump but I think it is related to using some very old, a bit gloppy, diesel additive ( I thought it would be the best way to get rid of it!) that caused a blocked inlet filter. PITA to fix, won't do that again.