Last year my check engine light went on. Went to dealer and was told I had a bad glow plug but it was not necessary to fix it right away and when I did I should just do all 8 since if I had one bad o...
I have the same engine as you. I had one burn out around the first of the year. I just got around to replacing it last month. I just burn out another one the other day. If I have time I will replace it this weekend. I would replace it when it gets cold though because "I" don't like fuel knock or rattle.
There is no danger to let it go as you said other than hard starting when very cold.