Hey guys,

I got a question for you. Does fogging oil foul spark plugs? I fogged my engine for winterization. I have my exhaust manafolds off because I'm changing them out for new. So I have easy access to the plugs. So should I change my spark plugs before I change my oil? Or should I wait and start the engine with the old plugs, change the oil to get the fogging oil out and then change the plugs? Thanks

9 times out of 10 yes.

Although it is temping to change them out while the exhaust is off (it will be alot easier), I wouldn't do it!!
Here's why...and I'm speaking from experience!! Leave the old plugs in while installing the new manifolds because it's very easy to crack the plugs when you are getting the manifolds in place, especially if it's a tight fit!!

Craig,

Cracking the plugs is not an issue for me. I just wanted to know if the fogging oil will foul my new plugs?

It does, and OS has a point but it is much easier now. You could slide some fuel line over the plug to give it extra protection when installing the exhaust, otherwise be very careful. It does make sense to change them no matter if now or when the exhaust is on though. Make sure the gap is checked on each plug. I could see how the heavy anchors they call "logs" could hit the plugs and crack them, you may not even know it happened and then you are chasing a gremlin. Now is the time to lighten them up...if it is in the budget because they are $$$$$$$$$$$$$$$.

My only issue is will the fogging oil in the engine foul my plugs?

the answer is simple and has been said before

YES
YES
YES
YES

that's not what he wanted to hear
so NO, it has never fouled mine

Considering the hundreds of thousands of boats that are fogged every fall and started up and run every spring on the same plugs Id say no, they wont. Or at least they will clear themselves when run.

yes, they will foul your plugs and yes change them out....