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Oil filter bypass valve #4594279
12/04/17 06:21 PM
12/04/17 06:21 PM
Joined: Oct 2017
Posts: 509
Northeastern Vermont
littleant Offline OP
littleant  Offline OP
Joined: Oct 2017
Posts: 509
Northeastern Vermont
Hi folks. Ran Mobil 1 5w30 with a Mobil 1 filter and currently running QSUD 5w30 with a fram ultra. When temperature is above 30 the oil light goes out about 1 second after engine starts. When temperature hits 20 and lower the oil light goes out when the engine is cranking. This happens with either oil and filter. Am I correct in assuming this is a function of the bypass valve. Never any noise


I can't prevent getting old but I REFUSE to grow up.
2010 Mountaineer 4.0
2002 Jeep Wrangler TJ 4.0
Re: Oil filter bypass valve [Re: littleant] #4594313
12/04/17 06:52 PM
12/04/17 06:52 PM
Joined: Oct 2004
Posts: 8,334
Cincinnati, OH, USA
bullwinkle Offline
bullwinkle  Offline
Joined: Oct 2004
Posts: 8,334
Cincinnati, OH, USA
Nope-the oil is thicker & builds up pressure more quickly.


06 Ram 3500 CTD 4X4(FG Venturi), 93 GMC C3500 6.2, 89 F-450 7.3, 98 XJ 4.0(XG8A), 05 xB(XG3600), 18 Transit 3.7, 03 Merc Grand Marquis 4.6 2V(XG2)
Re: Oil filter bypass valve [Re: bullwinkle] #4594337
12/04/17 07:09 PM
12/04/17 07:09 PM
Joined: Oct 2017
Posts: 509
Northeastern Vermont
littleant Offline OP
littleant  Offline OP
Joined: Oct 2017
Posts: 509
Northeastern Vermont
Originally Posted By: bullwinkle
Nope-the oil is thicker & builds up pressure more quickly.
Thanks bullwinkle


I can't prevent getting old but I REFUSE to grow up.
2010 Mountaineer 4.0
2002 Jeep Wrangler TJ 4.0
Re: Oil filter bypass valve [Re: bullwinkle] #4594397
12/04/17 08:14 PM
12/04/17 08:14 PM
Joined: Mar 2016
Posts: 1,652
Western S.C.
CR94 Online content
CR94  Online Content
Joined: Mar 2016
Posts: 1,652
Western S.C.
Originally Posted By: bullwinkle
Nope-the oil is thicker & builds up pressure more quickly.
Yes, because you get enough pressure to shut off the idiot light even at cranking speed.


2011 Toyota Prius now at 94K
1981 Mazda GLC (323) retired at 606K
1972 Subaru DL retired at 190K
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Re: Oil filter bypass valve [Re: littleant] #4595695
12/06/17 06:18 AM
12/06/17 06:18 AM
Joined: May 2007
Posts: 7,630
Indianapolis, IN
dnewton3 Offline
dnewton3  Offline
Joined: May 2007
Posts: 7,630
Indianapolis, IN
To be a bit more detailed ...

The oil filter BP valve has nothing to do with the engine oil pressure sensor. However, the cold thick lube will have an effect on the overall engine oil system pressure and how it interacts with the pump BP relief. Pressure is the resistant to flow in hydraulics. The pump is a positive displacement system, the oil is going to move somewhere, somehow. So if you are getting pressure a few seconds sooner, it's because it's resisting flow and building up pressure sooner. That does not mean it's getting no flow, but it's likely getting a reduced flow, contrasted to a warm oil.

Don't panic though; it really does not matter. I've not seen any evidence that this topic actually matters in terms of wear-rate data. You don't have a lot of ability to control this. You can select a thinner lube (typically down one grade, if you want), but that, too, does not really affect wear in a discernible manner. If you're already at a 20 grade, there's not much room to go lower anyway.

Last edited by dnewton3; 12/06/17 06:19 AM.

The act of preventative maintenance, in and of itself, is FAR MORE important than brand/grade/base choices among lubes and filters.
- under maintaining something is akin to abuse/neglect; that can kill equipment by shortening the lifespan
- over maintaining something has never been proven to be anything but a waste of time and money
Re: Oil filter bypass valve [Re: dnewton3] #4595834
12/06/17 09:20 AM
12/06/17 09:20 AM
Joined: Oct 2017
Posts: 509
Northeastern Vermont
littleant Offline OP
littleant  Offline OP
Joined: Oct 2017
Posts: 509
Northeastern Vermont
Originally Posted By: dnewton3
To be a bit more detailed ...

The oil filter BP valve has nothing to do with the engine oil pressure sensor. However, the cold thick lube will have an effect on the overall engine oil system pressure and how it interacts with the pump BP relief. Pressure is the resistant to flow in hydraulics. The pump is a positive displacement system, the oil is going to move somewhere, somehow. So if you are getting pressure a few seconds sooner, it's because it's resisting flow and building up pressure sooner. That does not mean it's getting no flow, but it's likely getting a reduced flow, contrasted to a warm oil.

Don't panic though; it really does not matter. I've not seen any evidence that this topic actually matters in terms of wear-rate data. You don't have a lot of ability to control this. You can select a thinner lube (typically down one grade, if you want), but that, too, does not really affect wear in a discernible manner. If you're already at a 20 grade, there's not much room to go lower anyway.
Thank you dnewton3 for the detailed info. With my 02 jeep with the 4.0 tractor engine with 170,000 miles I never worry about 5w30 HM every 5,000 its good. The mountaineer with the 4.0 with all the timming chains I watch it like a hawk. 68,000 miles


I can't prevent getting old but I REFUSE to grow up.
2010 Mountaineer 4.0
2002 Jeep Wrangler TJ 4.0

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