im running 2 year old champion spark plugs with 15k on them(had my timing advanced about 4 months ago). think its time for new ones?

 

probably not but take a couple out and inspect them. Too many variable effect spark plug life to say "yes" or "no"

Are they copper core or platinum? Straight copper core can be good up to 30K miles depending on driving habits, gas used, and overall maintenance of the car.

 

It was time for new ones 15K ago. I hate Champion plugs.

I use NGK V-power plugs in my 5.0.

 

half dozen of one, half dozen of the other. ::shrug::
NGK is a japanese plug in, an american car. I never thought that was right.

Anyways, 30K is typical for most non-platinum plugs.

 

what are good spark plugs to use for a mustang? im thiking about changing mine cuz not sure when was last time they was changed

 

autolite 25s

 

Exactly. Simple and cheap, work great!

 

if your car is running fine 15k is nothing, as stated 30 k for a standard copper core resistor plug, when it's time autolite 25's will be fine

 

I'm another one here for autolite 25's, never had a problem with them. Check your plugs now, see what kind of shape they're in and than take it from there.