Fill cracks surrounded by subfloor back fine art? Somehow I messed up the toung and groove on a couple pieces...

Somehow I messed up the toung and groove on a couple pieces of my workshop floor and now I have a crack between the pieices I stipulation to fill before I can paint. What should I steep it with? I heard bondo works, is this true?
Serious ? How do you burn dust incense?
Answers:    Bondo in reality works very well. Professionals use it on painted trim adjectives the time and I believe they even sell it in gallons at Home Depot.
If the cracks are smaller you may be capable of use other things like Famowood or Plastic Wood which is premixed, dries fast and sticks pretty all right. We use them to fill gouges and cracks contained by floors all the time.
Making a purse?
a flexible, paintable (latex) caulk is best, as walking on it will cause a touch "flexing" action. With a caulk gun, fill the cracks and after with a smooth blade, level it sour. You can then wipe off the excess around the crack next to a wet rag. If it is "subfloor" won't you be covering it next to something other than paint?
Painting strange cedar stairs and railing on front...
Use Elmer's glue and saw dust mixed together. Mix it within a bowl.Then with putty knife pack it surrounded by the crack let dry sand, and paint.