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Old 08-05-2011, 01:31 PM
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bluebee bluebee is offline
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Location: San Jose, California
 
Join Date: Mar 2008
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Quote:
Originally Posted by sealbeach740 View Post
Since this post has been brought back to life
Just for the record, this is the 'canonical' thread for how to change your oil using the gravity method ... so ... by virtue of that nomination ... it will consistently be the one thread we 'append' useful information to for ease of reference in the future, by others, long after we're gone.

Quote:
Originally Posted by sealbeach740 View Post
how does priming the oil filter help with cold starting an engine?
Good question.

BTW, in a somewhat related aside, cn90 posted such useful information today in the aforementioned oil-pressure thread (E39 (1997 - 2003) > Oil Pressure light flickers on while idlying), that I just have to repost it here for posterity:

Quote:
Originally Posted by cn90 View Post
1+,

Some mechanics are basically hack mechanics. The thing breaks and they just move on = not good!

To illustrate this fact, I redraw the Oil Filter Cap.
The 2 tiny O-rings' sole purpose: when you change the Engine Oil, the Oil is drained down the Oil Pan to be drained out and disposed of.

When the engine is running, these 2 tiny O-rings prevent oil from being pumped back to the Oil Pan. So when this tip (with the 2 tiny O-rings) is missing, some oil is pumped into the Oil Pan, thus "low oil pressure" light on dash during idle rpm.

At higher rpm, there is more oil pressure, enough to extinguish the light in the dash, but might not be enough for proper engine lubrication.






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PS: This is hypothetical but I will try to be as close to the numbers as possible.
- Usually the oil pressure light goes out when the pressure is above 8psi or so.
- OK, your Oil Cap Tip is gone, when you rev the engine to 2500 rpm, oil pressure is let's say 15 psi (instead of 30 psi), enough to turn the dash light off.
But the engine is designed such that at 2500 rpm, it needs around 30 psi for proper lubrication.
So at 15 psi, you risk engine damage.

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