oil pressure jumped after oil change

ranchos

Cadet
Joined
Feb 20, 2007
Messages
19
2005 tahoe q4sf/4.3l merc v-6, change oil (25-40w) & filter thursday, ran it on mouse ears no leaks(filter) must be good to go, at lake 2 days later 2 600am, got rpm's to 3000 up to 3800, oil pressure guage at 80psi, after a bit (time to get oil warm) backed down to about 42. stopped fished for while did same. rest of day didn't do. ran it today at home on mouse ears up @ 3000-3200rpm oil pressure guage would kind of jump up to @ 60psi when move throttle from 1000 to 3200. oil level on dip stick fine. what do you folks think?
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: oil pressure jumped after oil change

oil level on dip stick fine.

Does this mean that is was not too low and to high.
High oil levels (over the full mark) can create it's own problems.
 

ranchos

Cadet
Joined
Feb 20, 2007
Messages
19
Re: oil pressure jumped after oil change

oil level on dip stick at full mark, not over-ful
 

Bondo

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Staff member
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Apr 17, 2002
Messages
71,093
Re: oil pressure jumped after oil change

Ayuh,...

I would Expect the Cold oil pressure to be considerably Higher than the Warm temps...
 

Seadooman03

Seaman Apprentice
Joined
Jan 31, 2009
Messages
48
Re: oil pressure jumped after oil change

If your comparing your old oil pressure to new oil pressure, you have to remember that your old oil..(depending on how old it was) becomes less viscous, which would cause lower oil pressure as the oil breaks down and becomes polluted with fuel. New oil is thicker, and until it starts to thermally break down, you will have oil pressure spike. Especially when the oil is cold, due to the outside temperatures. From my understanding, as the oil heats up, the pressure comes down, which is normal. However, if your oil pressure did NOT come down, then you may of had a problem.
 
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