Fogging a 4-Stroke Engine

[bailey05]

I would like to know the proper way to fog a 4-stroke engine. I have twin Yamaha 250’s (F250TXR) and have had the maintenance done the past two years by the dealer. Each time the service tech came to winterize the engines he did all the necessary filter and oil changes and fogged the engines by putting a small amount of fogging oil into the fuel filter cup on the engine when he replaced the fuel filter. When he was finished with the servicing of the engines he ran them several minutes until a small amount of smoke was generated in the exhaust. Is this an adequate way to perform the fogging?

[robert graham]

Well, that way sounds fine, but I usually just spray fogging oil into each spark plug hole, crank motor over a bit to distribute the oil, replace plugs. Fogging through the air intakes is more important on 2 strokes because of crank area bearings and parts that need the protection.