Originally Posted By: d00df00d
On a cold start:
1. Oil is too thick
2. Clearances are too small
3. Fuel mixture is too rich
If you use too much throttle or rev it too high, you'll cause excess wear. You'll also load up your catalytic converter faster (more combustion byproducts) and may cause greater fuel dilution in your oil.
A turbo would worsen the excess wear if you're too eager to drive on-boost, and it's another part that'll suffer more with that too-thick oil.
Best thing to do on a cold start: let it idle for up to 30 seconds as StevieC suggests, and then pull away gently with the interior heater OFF. Drive mildly until it's up to temp. Then you can turn the heater on and drive as you want.
1. No it's not...as suggested, it has higher viscosity, keeping parts mechanically separated. There's a reason that the Sequence IVA uses 65C as the test point. The oil is thinning, and the additives aren't functioning yet. Bobbydavro advises that he's done the test at colder temperatures (thicker oil) and hotter temperatures (thinner oil, better additive activation) and both cases are better wear wise (camshaft) than the test temperature.
2. No they aren't...an Aluminium piston in an iron bore will have greater clearance cold than hot. A steel crank in an iron block, they will both shrink expand the same for a given temperature. Crank will heat faster than the block, but the delta in clearances is tiny.
3. Yes, agree, but the doomsday scenarios that follow aren't realistic.
VP, it's best not to thrash an engine until everything is happily at temperature, and you are in a range that the additives are fully functional...but a bit of a squirt to manage traffic isn't that much of a biggie over the course of your ownership.