When ever my truck sits for for id say over 6 hours, I get a ticking/rapping on start up that last about 2 seconds. Please tell me im bugging cause my truck only got 88k!?
It takes a couple seconds for the oil to get from the oil pan on the bottom of the engine to the top to lube up your lifters...it occurs with everyone.
You might want to try a better quality oil filter with a reliable anti-drainback valve...and perhaps a better engine oil too. Mine doesn't make any noise whatsoever from the engine internals regardless of temperature or time not running.