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      02-18-2019, 12:43 PM   #425
deansbimmer
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Drives: 2011 E93 M3
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Quote:
Originally Posted by Scharbag View Post
Not really - oil film is still there and when your car starts, it does so under no load conditions and at low RPM. Relative to the forces seen at 8400RPM, startup is not even worth talking about.

Regardless of warmup etc., if your bearings are too tight, then you will need to replace them or risk spinning one of them.
No, it is a fact that in normally operating engines the most bearing wear occurs at startup. Wear is occurring to the bearings until oil pressure builds which produces the hydrodynamic bearing that the crankshaft rides on during operation. Under oil pressure this fluid bearing prevents the physical contact between bearings and journals.

In addition to every startup, engines with unfavorable tolerance stacking from the factory are hit with the double whammy. Its why we see "babied" engines fail just like those that are tracked. How the engine is treated only speaks to a portion of how the bearings will wear.

You can read about how engine bearings work here:
http://kingbearings.com/files/Engine..._They_Work.pdf
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