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2003 GMC Safari AWD
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113 Posts
Discussion Starter · #1 ·
Had a purolator on from the last oil change. sometime while driving, not immediately after oil change, but somewhere in between, my oil pressure gauge dropped from its usual, (which was- over 50 while warming up, driving around 40 and then at idle somewhere around 20?) to only 20-40. I've read about it and it seems the gauge is notorious for being inaccurate and that as long as it never went to 0, I may be good. However, after the purolator it never seemed to get above 40, ever. I didn;t realize all of this until I changed my oil the other day. Got a mobil 1 filter this time. and now I am baclk to over 50 warm up, constant 40 while driving and 20+ at idle. Does this make any sense and is purolator something to avoid? I have eliminated my oil cooler, a while back. The oil filter that is recommended seems to me smaller than it should as I have AWD and it is tight up in there. any thoughts?
 

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2000 Lifted 4x4 Astro 92 V8-350 Shorty
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My best guess... oil filters have a "bypass valve" (in case filter become too clogged or over-pressurized). Maybe the valve was defective/open in that filter reducing back pressure. Technically it shouldn't hurt anything (except that oil is no longer being filtered)
Font Line Parallel Diagram Engineering


PS: Your oil pressure values appear just like mine
You can use short or longer filters.
I've been using ACDelco PF-52 filters in my 2000 (available at Walmart)
 

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2003 GMC Safari AWD
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113 Posts
Discussion Starter · #3 ·
My best guess... oil filters have a "bypass valve" (in case filter become too clogged or over-pressurized). Maybe the valve was defective/open in that filter reducing back pressure. Technically it shouldn't hurt anything (except that oil is no longer being filtered)
View attachment 285548

PS: Your oil pressure values appear just like mine
You can use short or longer filters.
I've been using ACDelco PF-52 filters in my 2000 (available at Walmart)
My best guess... oil filters have a "bypass valve" (in case filter become too clogged or over-pressurized). Maybe the valve was defective/open in that filter reducing back pressure. Technically it shouldn't hurt anything (except that oil is no lo
 

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2003 GMC Safari AWD
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113 Posts
Discussion Starter · #4 ·
I am not sure why that post above made it that way? All I was trying to say is thanks, you learn something new everyday. I was wondering why my oil look dirtier than usual. I will keep a better eye on all that and know what to look for next time. Thanks again MM.
 

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2000 Lifted 4x4 Astro 92 V8-350 Shorty
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5,998 Posts
It was just my "best guess"... I can't say for certain this is what happened.
Seems problem went away with new filter.

It does raise concerns for all of us when pressures vary from norm (after oil change)
I've never really considered this happening, until your post.
Usually with fresh oil, pressures are almost always a little higher at first.

But none the less, glad it is resolved.
 
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