I have a 1990 Honda Accord. Sometimes, when starting up after sitting for a long time, I get blue smoke from the exhaust. This only lasts for a minute or two, after that, there's no smoke whatsoever. I've also found that if I let the engine idle for a minute after parking, instead of shutting it off immediately, then there's no smoke when I start up again.
The signs point to a faulty valve gasket. But since this is fairly complicated to fix, I'd like to first eliminate any other possibilities. Is there anything besides a faulty valve gasket that could be causing this? (On another forum, someone suggested a PCV valve replacement for a similar problem. Does this make any sense?)