I might want the factory description of how the cdi glow plug system works. The early non Mercedes but possibly manufactured under licence by them cdi engine we had started easily at temperatures many gas engines would not start.

The engine noises where so bad I felt that a block heater was needed. One was as not available from the factory for that model. Some people put stick on oil pan heaters I suspect for the same reason.

We just never used the car at really low temperatures as we had others. This issue was only a few early mornings each winter at most. . Minus thirty degrees F and lower. Strange but we never have temperatures that low anymore locally . Not even close. This winter will set records locally for the low amount of heating energy used probably.