Bests & Worsts Reviews from Amazon

I'd wager that most of the 5 star reviews haven't pulled their spark plugs recently. I pull mine every year or two in preparation for smog. I've used Lucas occasionally for years, but last year I decided to buy a gallon of Lucas and use the recommended dose with every refill. What a mistake. I pulled the plugs, and they were covered in an ashy crud. I've never seen plugs so badly fouled, so I used a spark plug diagnosis chart and sure enough: ashy fouling caused by fuel treatments/additives. Never again!