Just reading a post from a guy with a '95 e300d, one glow plug got stuck, wouldn't come out. To contrast that, I previously asked my parts place about replacing my glow plugs for the 90k service, but they said don't worry about replacing glow plugs, only replace them when they won't work anymore (we're in warm climate of Atlanta, GA). I wondered if I left them in a longer time, would they get stuck? My car is 15 years old, just got it recently, so I don't know the last time they've been replaced, maybe never. I know when putting them IN, you're supposed to use anti-sieze. But if I "let them go until they don't work", will they become increasingly harder to take out as time goes on?

1991 300d, 90k

Carbon builds up around the shaft and locks them in, this is mostly a 606 problem. If I owned a 606 I'd ream them every year, but only change them when they went bad.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

The stuck glowplug syndrome effects OM606 engines, your car is equipped with an OM602 engine. The OM602 does not suffer the stuck glowplug malady.