I like to air on the side of caution! I tend to remove or replace possible problematic parts once identified or when they have known issues and are not cost prohibitive...
That being said; based on some of the dire warnings posted and the possibility of catastrophic engine damage as of the results of a failed ceramic glow plug, they got my attention!
Being proactive, and since ID parts put their 7v Etecno Glow Plugs on sale this month, I went ahead and ordered a set and plan on replacing them ASAP....
I certainly believe it is better to be in the "I rather be safe than sorry" group...than in the "Well I told you so" group!
Just glad I do not live in the very cold winter climates areas and have to weigh the performance factor of GP's into a decision...

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Supporting Vendor and Moderator of LOST05 Jeep Liberty CRD Limited 
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount98 Dodge Cummins 24 Valve