Runnin in oil doesnt have any friction modifiers. Its ability to lubricate will not change just because its colder, or hotter. It will (unless its cheap running in oil) more or less stay the same. Only downfall that i can guess ( n this is from the old guys that ive learnt from) is that it doesnt last as long.

As for not taking ur engine here.. good We're busy enough!!!

first 10 mins??? now i take it, that ud let the engine idle for those 10mins now wouldnt u