1990 Honda CRX tail pipe blows white smoke

My 1990 Honda Crx si blows white smoke when starting engine but goes away, I checked the radiator and I found some brown oil residue but the engine runs great. The other thing is that after a long ride and I shut the car off, it won't start up right away it takes a while, but while trying to start up the car it sounds like a filter of some sort is dirty and cause the engine not to start.