Locoming SB
There is a Lycoming SB or SL on the subject of minimum oil temp for take off, at the airfield I operate from this is never an issue so my memory is a little hazy but I seem to remember it saying that if the engine will idle at 5-700 rpm smoothly the engine was walm enough for take off.
When I get into the office I will try to dig out the SB/SL and send you the reference.