I warm up my engine as well. I use the scientifically proven best way to do that: by driving the car gently until not only the water, but also the oil are warm. We're talking 20 minutes in Southern California weather here.
Agreed! Idling a car to warm up is not doing it any favours. once the oil had circulated to all the required areas, it needs to be driven to warm up properly.
If you live in a cold area, and are worried about cold start protection, buy better oil - a 0W-XX will give the best startup protection, as it doesn't thicken when cold anywhere near as much as other oils.
Idling a car does NOT warm it up evenly, and certainly isn't warming up any other parts of the car, like the trans and diff etc. You've likely heated the pistons, head, coolant and exhaust valves. The rest hasn't warmed up, but you drive off, thinking it is.
Idling is the slowest way to warm an engine. Idling also does very little to raise the oil temps, and that thick cold oil (especially if you
still use SAE 30) is what's causing the wear, as the flow is reduced when it's thick (That's what causes cold start wear). Flow is what protects the engine, not the pressure (otherwise an "A" engine wouldn't work, without pressure fed bearings, pressure in modern engines just gives better supply flow).
So with idling, you sit there with it doing a whole lot of cold revolutions with cold oil being pumped very slowly through the engine. Then drive off with warm coolant, and still cold oil.
In the vehicles I've had with an oil temperature gauge, the oil temp takes about twice as long to get to temp as the coolant does. Even my Aircooled VW's would have the air thermostat open (and the head temperature up to normal, when fitted)
well before the oil temps were up to normal.