[King-Aaron]

The difference is that your pistons, rings, bearings, etc have not come up to operating temperature and have not expanded due to heat. It's not going to explode immediately but you are reducing the overall lifespan of the moving parts if you drive on a cold engine.

Most modern cars are a lot more tolerant thanks to advancements in oil technology. But it is to a greater or lesser extent better to warm your car up, even if it's not immediately / apparently necessary to you.

[blattimwind]

You're not supposed to floor it and giver 6.5 when she's cold. Driving with low loads and low RPMs will bring it quickly up to temperature and produce minimal wear; I've been told it actually produces less wear as the engine runs less time/revs cold.

It's a different story if you're pulling a heavy load and can't do anything about it. Then letting her warm up makes some sense. Most people don't do that.

[King-Aaron]

Yeah thats right. I build race engines as a hobby (currently have a cp-carrillo mazda BP in the works) and (I like to think) I have an understanding of mechanical sympathy. Obviously performance engines have different tolerances to mass-produced consumer items, but I like to treat them the same.

The benefits to slow driving is that it also brings the drivetrain up to operating temps as well - it's no good if the engine's at a good oil temperature but the differential and gearbox is still icy. But even letting the car idle for 10-20 seconds so it can push oil around the block, fill the galleries and start filling the lifters/head will help extend the lifespan of an engine, and then combined with a slow initial drive to allow everything to come up to temperature you should be able to give the car a bit more life.