I have a 1993 Suzuki 175 which has been very well maintained and looked after. Recently it started losing power and it ran on 4 cylinders. On inspection I found the plugs were fouled. I replaced them and within 2 to 3 hours running the problem repeated. My mechanic tested compressions (all okay given age), tested electrics, replaced head gaskets and the problem continues. It has occurred to me that the oil I use (quicksilver) may be a bad batch. Has anyone had similar problems with Suzuki or other engines and could oil be problem. Otherwise with new set of plugs, the engine still runs as sweetly as it did new.
