Recently I bought a 96 accord. I know it needs a few things done to it, it's been sitting for a year. Yesterday I realized it needs a new vavle cover gasket and spark plug gaskets. It doesn't over heat and runs a little rough at an idle, but not bad. 3 days ago I put lucus fuel injector cleaner in it and noticed after sitting all night then starting it in the morning it blew white smoke out of the exhaust for a min or 2. Then it cleared up and only does it after the car sits for hours. Wanted to know if this was common with that fuel injector cleaner because it didn't do this previously.

 

youre going to need to compression test it to be sure the head gasket is still sealing

 

This is a sign that coolant is leaking into your cylinders and burning. You can do a compression test, or a combustion leak test (also called block test) to find out for sure. This may mean a damaged head gasket, or worse cracked block, although in your case it may be the former. You can try Steel Seal or something similar from your local car parts store to try to fix it.

 

Was there any white smoke prior to adding the fuel injector cleaner? If not, I would say that it was nothing more than residual fuel injection cleaner.

Now if it is still doing this a week later with new fuel in the tank, I would say coolant in the combustion chamber and you should look into a coolant system pressure test. I prefer the coolant pressure test over the compression test when looking for coolant entering the cylinders.

 

Depending on how much smoke you are talking about it could just be condensate turning into steam, especially if the air is humid where you live.