Antidrainback valve, restricts flow?

[Patman]

I've heard this before, but is it true that the filters with antidrainback valves restrict the oil flow somewhat?

Out of the two longer filters I can use on my car, one has an antidrainback valve (PF1218) and the other (PF35) does not.

I don't really need it anyways, as my filter sits vertically anyways, and gravity makes sure the filter is full when the engine is shutdown.

 

[BOBISTHEOILGUY]

Not enough that it would cause a problem.

As for no drainback valve needed, wouldn't the effect of gravity allow the oil to drain back through the filter(in a sense backwashing the filter) into the oil pan, therefore leaving the oil channels from the filter where the oil settled down to, up to the top of the engine virtually with no oil? That is the main problem with no drain back valve and will cause it to clatter when first starting.

 

[VaderSS]

That's a good point and one I had never thought of.

 

[Patman]

I'm glad I have a choice then, I guess I will make sure to always get the PF1218 from now on then!

I don't hear any clatter on startup mind you, but that's probably the moly protecting me!

 

[Patman]

Now I'm confused. I just did a search on CamaroZ28.com on this subject and found the following post:

quote:

---

I have used both filters, the PF35 and PF1218, and I saw slightly lower oil pressure with the PF1218 from the restriction the anti-drain back feature poses. Either should work fine, but I switched back to the PF35 after using the PF1218. I have always used Mobil 1 synthetic 10W-30, so it wasn't oil viscosity that changed it. Just my experience.

---

 

[Patman]

On my way home from work tonight I kept a close eye on my oil pressure gauge and it's true,
it does seem that the oil pressure is lower with this PF1218 filter (compared to the PF25 I had
before, which like the PF35, doesn't have the ADB valve)

So based on this, which would be more important, having that oil flow at startup, or having
better oil flow the rest of the time? I'm thinking the PF35 might be my best choice after all,
especially with the hard driving I do. I don't want to be starving for oil flow at high rpm.

 

[VaderSS]

Does the PF25 have a drainback valve? If not then there is probably one on the engine and none is needed in the filter, if so, then you should run a filter with a drainback valve. I do not think that a slight reduction in pressure is going to hurt anything if that is the way it came stock.

Just my $.02

 

[Patman]

Nope, the PF25 and the PF35 filters do not have the ADB valve actually.

I know these engines have the bypass valve in the block, but I didn't think they had an antidrainback valve there too (but I could be wrong)

[ June 25, 2002, 10:45 AM: Message edited by: Patman ]

 

[VaderSS]

I'd not worry about it then.

 

[widman]

First, where is the oil presure sensor? Before or after the filter?
Second, low pressure is not necesarily bad. The pump produces "X" amount of force. That is then divided between pressure and circulation. As long as the pressure is over the minimum for the engine in question, I'd rather have more circulation and less pressure. To see, just close the nozzle on your garden hose till you get a lot of pressure....... and see the reduced flow.

 

[Patman]

I'm honestly not sure where the pressure sensor is on my LT1. From what the guys on CamaroZ28.com say though, they are getting lower pressure with this PF1218. I switched back to the PF35 on my recent oil change on Friday and I notice the oil pressure is back higher again. Not a huge amount, but maybe 3-4psi more at highway speeds (40-42psi compared to 37-39psi) compared to before. Idle oil pressure is still the same (20psi once warmed up)

 

[Terry]

Patman, If you have a increased resriction the pressure will increase, like others have said less pressure is good as long as it is enough to propel the lube wedge to all bearing surfaces. By dropping pressure to the min allowable you reduce restricted flow and increase HP!

Do the feel check on the new filter and make sure it is not in bypass mode. If it is bypassed you may also have less restriction. In your engine the bypass valve is in the engine above the oil filter pad.

I 've never heard the theory about the anti-drainback valve changing oil flow or increasing or decreasing restriction. Heck its just a rubber grommet.

 

[Patman]

Terry, if this were your car, which would you choose, the filter with the antidrainback valve,
or the one without?

 

[Bror Jace]

Yes, I run into this often. Pressure = resistance to flow and lower pressure may be a greater amount of oil in all the more important places.

Keep in mind, presence of oil (greater flow) protects your motor, not pressure. When I was a fireman, we used to talk about water putting out fire and NOT pressure although some people believed the opposite.