Aside from all the BS posted here......it is always a good idea to allow ANY engine, gasoline, diesel, or gas turbine to warm up to recommended operating temperature before driving or putting it under a load. Adequate warm up allows for complete expansion of metal components within the engine,(minimizing wear),ensuring consistant oil flow (viscosity), and even best intake manifold vaporization of fuel.
Until the designed temp is reached, the engine is NOT operating at maximum performance and efficiency. This is why there is a heat riser system (exhaust/intake manifold), and thermostat in the cooling system to aid in warm up. Carbs with a temperature controlled choke valve depend upon engine temp to dis-engage also.
Modern day engines with computer controls actually operate in an "OPEN LOOP" mode until a pre-set engine temperature is reached then the electronics kick in to "CLOSED LOOP" whereas the timing and emmission control systems are modified for maximum performance and fuel economy.
The bypass in the oil filter is not an issue, approx 10% is bypassed at all times hot-cold or in between.
