I have a 2000 Johnson 25hp 3cylinder. The sticker shows QL82C. But the Johnson spark plug guide says QL86C. Is there a difference and which one should I use?
If the Johnson guide you refer to is a later, and official, list go with its recommendations otherwise stay with the original QL82C unless you have trouble with plug fouling with prolonged low speed running. In which case try QL86C.