Borescope
 

Would a borescope be effective in spotting carbon problems in the RX-8? Right now I am using the sparkplugs as a proxy, and mine have a lot of carbon (black) after just 4,000 miles. And I was misfiring during warm idle. It may be the colder temps here in MN, but I gotta make it run well year around.

So, I want to set up a better monitoring program. Will a borescope help me do that? The first time i would do a before after with Seafoam sucked straight into the combustion chamber. If i can see the difference, next i would determine how often i need to do the decarboning.

Can i see other things like my apex seals, side seals scoring on the inside walls?

Not really.
The view through the spark plug port or down the intake manifold doesn't really give you an angle on the grooves that get gunked.

I've got one that I use for various "around the corner" looks, but other than looking directly at the face of the rotors or the faces of the irons, it doesn't show you much on an "in situ" motor.

Thanks for the fast, expert answer.

(I updated my miles and symptoms above. This is with 1/2 oz Amsoil Saber Pro per gallon.)