compression test question

And Gulf Oils cheap line. Gulf was swallowed by Petro-Can back in the 80s I think. That stuff was horribly ashy. Back then I was pro-Canadian, and Petro-Can was Canadian so I bought that stuff. My plugs kept ash-fouling, and being young and unlearned, I didn't put it together. Eventually that teener had to come apart. Well there was a lot, a LOT, of ash stuck in every crevice, nook,and cranny. I never bought another can of that stuff again, and it never fouled another plug.