Ive been reading some about what type of plugs i need to buy/use for my hemi. (04QCHemi) and i guess i was under the usumption that the origional spark plugs are suppose to last 100,000 miles before you need to change them. But i read i need to change them at 30K? Are they just break in plugs? What gives?

 

No, they aren't break-in plugs. It appears the Hemi's don't like platinum plugs. Some say the platinum plugs can cause a drop in fuel mileage and misfiring, copper plugs seem to be how to go. Others say they run platinums and don't have a problem. This thread should help answer your question: https://dodgeforum.com/m_661636/tm.htm

 

I have ran the Autolite Platinum plugs in three trucks with no problems .
More than likely the reason the factory uses copper plugs is cost.
You do the math . Thats a lot of savings just by using standard plugs.
Then add in the fact you have shorter maintenance intervals and you are set.