I asked them to clean the block after the work was done because i was bringing it home to assemble. and i was told the oil passage plugs were removed and cleaned. thats why i thought it was done. who knows maybe they forgot. still charged me for it though. The main thing is that freaky things can happen durring a rebuild.. no matter how good the parts, oil or filter. If your rebuilding or buying a rebuild theres a few things to ponder. I double check my own work. I might even pull the pan and try primimg it to check for good flow before putting it in the rig.. or just fire it up once i finish the head.