In a V8 Mopar with aluminum heads and a
Mopar Orange ECU, what is the interval of
changing spark plugs, now that we all run on
unleaded? It used to be 10,000 or so, but that
was with points and leaded gas. Most of the
mileage is highway. I have standard (non‑platinum)
plugs.
The factory recommendation is 30K,
based on published specs from â€80s
carbureted V8 Mopars. Many factors can
affect plug life. Some engines just seem to
be harder on â€em than others for a variety of
reasons. As you obviously know, fine-wire
plugs, such as platinum and, even better,
iridium, do seem to last longer.
Obviously, if you detect a misfire at
something earlier than 30K, take a look at the
plugs, especially see how much the gap as
grown.