I was thinking....

[Morcos]

Since most of us are anal-retentive car enthusiasts, someone might be able to clear this up. OK think of this: your changing the oil, replace oil filter WITHOUT PRE-FILLING. and you add in new oil then close the filler cap.

the question, is there unwanted extra air in the engine, (ie: oil pump got air in it, oil filter has air in it) would this affect pressure?
am i crazy?

 

[Morcos]

if so, wouldn't we have to open the filler cap after a couple of minutes of driving, to release pressure?

 

[pitzel]

Engine crankcases are maintained as close to atmospheric pressure as possible throughout operation. PCV valves and breathers ensure this. If this were not the case, elaborate construction methods would be required to enclose an engine's crankcase and valvetrain in a pressure vessel.

Intake manifold vaccum quickly gets rid of any 'extra' air that may be present.

 

[Mike_dup1]

quote:

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am i crazy?

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Yes

Have you ever removed the oil cap, pulled the dipstick and heard a pressure release? NO...

 

[medic]

have you ever taken off your oil cap and heard a psst sound, similar to opening a pepsi bottle? If not, then I don't think you have anything to worry about.