2015 FB2.5 Legacy, Larger Oil Filter 30psi

[327amc]

Tired of the tiny pathetic stock oil filter. Going to Wix 51287 with 30psi bypass.

 

[keith3267]

The correct bypass for this engine is 8-13 psi. You could starve your engine with a 30 psi bypass. Also bigger is NOT better when it comes to oil filters.

Today's engines and oils do not get contaminated like they did in the old days. The engines are well sealed against contaminants, the rings seal better so there is less blow-by and the oils tolerate much higher temperatures so they don't break down like they used to. A smaller oil filter allows the engine to build up oil pressure much faster than a large filter which is critical to the life of the motor.

The oil bypass valve is a delta-p valve, meaning it is inline. The higher the delta-p, the lower the oil pressure on the output side, and the output side is the critical parts of your engine. You do NOT want lower pressure there.

 

[327amc]

I was under the impression the bypass for this motor was 23.2psi.

This engine, although it runs great, and is well taken care of, has the dirtiest oil of all my vehicles. I can go 10,000mi on my old 2.2L 4cyl chevys and LS engines and still have amber colored transparent oil. In this subaru its black after 500mi. Not to mention have to add a qt of oil about every 7000mi.

I run amsoil.

 

[327amc]

The correct bypass for this engine is 8-13 psi. You could starve your engine with a 30 psi bypass. Also bigger is NOT better when it comes to oil filters.

I dont believe that is correct. The bypass is simply the pressure at which the filter pushes the bypass valve/spring open, thereby bypassing the filter.

 

[Bill-A]

You'll want to check out this video if you want a larger filter AND a comparable bypass. Also note the first comment from MrSubaru1387 (a recognized Subaru guru).

 

[keith3267]

I dont believe that is correct. The bypass is simply the pressure at which the filter pushes the bypass valve/spring open, thereby bypassing the filter.

That is the bypass for the WIX filter specified for this engine. This type of valve is called a delta-P or dP. It opens based on the difference in pressure on both sides of the valve.

For example if the oil pump is sending 45psi into the filter and the oil pressure on the output side of the filter is say 42psi, it remains closed. If after several thousand miles, say 7000 for example, the filter media has collected enough debris from the oil to drop the pressure to between 37 to 32 psi, then the bypass valve would open to allow more oil to the critical parts of the engine.