Sea foam during winter?

Hello everyone, finally bought up my rx8 and have been loving it. The only issue I've been having is one that could be the worst. I've been having hot start issues somewhat recently and wanted to give the engine a cleaning to see if carbon build up was the issue. I also am unsure how old the ignition is on the car and I was planning on buying a BHR ignition for my 8. But first I want to make sure the engine is still even worth my time before I start to put money into it. What I'm trying to get at here is I do live in the New England area and it has been a brutal winter as of late. Now I've read that once you inject sea foam into the engine it should sit there for about 2 hours. Being where I am it is very cold and I just wanted some insight on if I'd be able to sea foam the car like any other time of year, or do it a different way. Thanks for any info