Help me figure out bypass settings

[Patman]

Do I have this correct? If I'm looking at two filters in the Purolator catalog, and one has a
relief valve psi of 8-10 and another is at 12-15, does that mean that the one set to 8-10psi
would go into bypass mode more often on the same engine?

The longer filter I'd like to run in my wife's Honda has a relief valve psi of 8-10psi, but her
stock filter's setting is 12-15psi. This filter would be otherwise perfect to use, as it's a lot
longer. But I'm just worried about that lower bypass setting.

 

[BOBISTHEOILGUY]

You have to consider that some filter medias are more restrictive than others and that will play a big role on how often it will go into bypass mode. Just because the setting is lower, if the filter media is less restrictive, then the flow would be more through the media.

 

[Patman]

OK, to make things easier, both of these filters are identical media, they are both Purolator
Premium Plus filters that I'm trying to decide on.

 

[ShootingStar]

I posted this in another thread and am now bringing it here:
Does this mean that the filter will be in bypass anytime the oil pressure is over 8-10 or 12-15 psi? If so, it would seem that cruising down the highway at 3500-4000 rpm for 1500 miles, you'd be in almost constant bypass and not actually filtering any oil! Maybe I just don't get it. Help me!! I'm a oil rookie!

[ September 07, 2002, 08:10 PM: Message edited by: ShootingStar ]

 

[ShootingStar]

Praise be to GOOGLE! I think I found my own answer. It's not the oil pressure, it's the PRESSURE DIFFERRNTIAL between the in and out of the filter.

The more I LEARN, the less I KNOW!

[ September 07, 2002, 06:23 PM: Message edited by: ShootingStar ]

 

[satterfi]

I'd go with the higher by-pass setting. Also, don't assume a longer filter cartridge has more media. Cut each one open, remove the media and stretch it out flat and measure.

You don't need to ask me why you have to go through all this trouble.

Edit: How do know the media is the same?

[ September 07, 2002, 07:09 PM: Message edited by: satterfi ]

 

[Patman]

I don't know for sure that the media is the same, but I would assume that most oil filter makers are not going to use different media within the same line of filters. So all the PureONEs would use one type of media, and all the Premium Plus filters would use a different type of media, but within that line they would all be the same. Why would Purolator go to the trouble of having more than two types of filtering media?

 

[MolaKule]

The filter with the higher by-pass setting should keep filtering longer until it loads up, the oil is very cold, or the oil pump pressure causes the filter to exceed its flow RATE, such as at high RPM.

 

[Patman]

quote:

---

Originally posted by MolaKule:
The filter with the higher by-pass setting should keep filtering longer until it loads up, the oil is very cold, or the oil pump pressure causes the filter to exceed its flow RATE, such as at high RPM.

---

So based on that do you recommend I should stay with the stock filter and it's 12-15psi setting over the longer one with the 8-10psi setting?

 

[jason07-1zzfe]

Ok just bringing this up again because I don't think a definitive answer has been stated and it's bugging me now

When EXACTLY is a filter in bypass? I know it is when the differential pressure is above the setting in the bypass spring. But WHEN does that happen? Or how can I find out? If I could have a differential pressure guage on the filter, or get another pressure guage before the filter(since OP is taken after filter) then it would be easy. But since the oil goes directly to the filter after the pump, it doesn't seem easy.
I'm just wondering at what system pressure does the filter go into bypass and how much sooner after it has been used for 3k, 7.5k...12k...?
I thought someone (Molakule, Terry?) said it will basically be in bypass at anything except warm idle.

If that is the case, why even have a filter, much less worry about all these PureOne/M1/Bosch Premium, high efficiency filters??
And you could try and find a filter with higher bypass like Patman is doing, but wouldn't that cause lower flow than the engine mfr intended, thus actually increasing the wear. Opposite of intentions...

Please help. I am doing this:

soon I will look like this:

 

[TooSlick]

Jason,

The primary time when the filter is in by-pass mode is while the engine is warming up. If you look at the relative viscosities of even a 0w-30 synthetic @ 40C (104F) and 100C (212F), you can see why:

Series 2000, 0w-30

Viscosity @ 40C ...57 Cst
Viscosity @ 100C ...11.3 Cst

To put this in perspective, a straight 50wt oil has a viscosity of 16.5-20.5 Cst @ 100C. So no matter what oil you use - even the lowest viscosity synthetic - it is much, much thicker while the engine is warming up.

It is pretty rare to clog up a filter in a gas engine, unless the oil sludges up terribly from overuse or coolant contamination. The short periods when you are winding out the engine on hard acceleration aren't much of an issue either. I'd say you are in partial by-pass mode during that time.

However, if you are doing short trip driving in cold weather and using a high viscosity oil, you really aren't filtering it much ....