Um, you got that one completely wrong. There is LESS friction when the oil is up to temp. Viscosity DROPS with temp increase. Why would you want more friction while you are driving????

Doesn't the car have to be at temp before VTEC will engage? I know it won't if oil pressure is too low, so maybe when the car is cold, it isn't engaging and you are getting a torque bump from remaining on the low RPM cam lobe when the secondaries open.