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Old 10-21-2008, 12:42 PM
franka franka is offline
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Location: Lakewood
Join Date: Jan 2006
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Mein Auto: E39 540i Sport
I've read that synth is superior in cold starts to dino oil because it will cling to the part for 5or 6 days where the dino is 2 to 3 days max, same conditions.

The main and rod bearings in your engine are lubricated by a process called a hydrodynamic wedge. W/o going into the details this process drags the oil with the rotating component and raises the pressure to 8 to 10,000 psi in the bearing preventing metal to metal contact.

So when you motor is running the crank and the rods are supported by the wedge (that can be around 0.0008 thick) so no metal to metal contact occurs, even under the pressure of a cylinder firing.

But when the engine is cold and started there is bearing material to crank main and rod journals surfaces. There is metal to metal contact until the hydro-wedge is established. And that takes time for the oil to get to the bearings in sufficient quantity. So the better the oil clings the better it lubricates. This is why you should give your engine a minute to get the oil circulated before you put a load the 'dry' bearings.

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Last edited by franka; 10-21-2008 at 01:45 PM.
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