Sorry Peter, no offense intended at jabbing Volvos as "very safe cars for people who dont like to drive".... but this is image they project, and the way many of them are driven.

In similar fashion, am constantly poking BMW owners with the comment "BMW builds better motorcycles than they do cars."

Btw, am in full agreement with you about changing all glow plugs together..... comparable to changing all the bypass fuel lines if one starts leaking - preventive maintenance.