Originally Posted by
trism
I dont think you are understanding how oils work.
Oil is not like water. It does not run off a surface as soon as you stop circulating it.
Oils are designed so that they cling to surfaces long after it stops being pumped around. As soon as you crank the motor over, it is turning the oil pump, sending oil around the motor. However, there is still a residual layer of oil left on the bores, and on the pistons. Thats why the oil business is worth billions of dollars, because they have the technology to make this happen.
So you crank the motor, and it kicks, and instantly, there is oil circulating around the motor, into the main bearings, around the cam journals, and onto the bore.Instantly.
The reason we have multigrade oils (ie Xw-X) is so that it is thinner when it is cold, allowing it to move around easier. After 30 seconds of running, all of the engines surfaces are sufficiently covered in oil. By sitting there any longer, its causing fuel wash, like i said before, where the excess fuel from the richness of the cold start is scrubbing the oil off the bore, leaving bare metal for the pistons to scrape up against.
If you were to drive off straight away, the engine is under load, so all of this fuel is burnt, and doesnt wash the oil off the bore.
Obviously you arent oging to bounce off the rev limiter, but please, please understand that you can drive after 30 seconds of starting the engine, and it will actually be better for the engine then letting it idle for 5 minutes.
There is a serious difference between letting your car idle to warm up and idling in traffic, the predominant reason being that which i explained earlier, when you start your car up, the engine is in cold start mode, and pumps more fuel in to avoid stalling, which doesnt happen when the car is already warm.