Lots of soot

[skno]

When I switched to 87 under the advisement of this thread I believe. My soot went to virtually nothing. The premium was a soot monster on my 454. I notice no change using the 87 octane.

[vans]

My carbureted boat had soot, usually the worst upon startup, I would jump in and chamois off almost every time I used boat, weather permitting.
My Cobalt, fuel injected, doesn't seem to have that issue.
Both boats usually get mid grade, with an occasional tank of premium