my zed has been well serviced all of its life and has high oil consumption. Have no doubt it's been like it most of its life. Bought it at 56k its now on 74k after a further 3 years. I've not had one problem in that period of time and I mean that. Changed wear tear parts, that's it. It's a daily driver too. Two oil changes in that time and about to do the third. So will compression test be the best way to check if its got problems?