Oil filter and related oil pressure

[Stefanovich]

Hi guys, l have a technical question that l hope someone can clarify. I’m using the GTR filter in my 23 Proto, It’s my understanding that this filter runs a lower bypass relief valve than the standard Z filter (GTR - 15 PSI) (standard Z filter 36 PSI). Given that normal engine oil pressure is above 15 PSI does that mean all unfiltered oil is being bypassed to the engine?
I’m also running the oil solenoid delete plug. Feedback much appreciate.

 

[Mugzilla]

Bypass is if the pressure DIFFERENTIAL across your GTR filtering element reaches 15.1 PSI. There isn't a gauge to measure the pressure drop across your filter. But it is there.

Oil pumps in car engines are all positive displacement pumps. They are going to put out a specific volume of oil at a given RPM. No matter what. They are NOT like a garden hose that you can throttle their output to cause lower volumes/pressures of oil at their discharge.

So what did Nissan do to save 0.2MPG? The bypass solenoid. (See multiple topic on this).

If you slap in a fresh GTR filter, and the filter elements are not clogged, there will be a pressure DROP from the one side of the filter elements to the other of, say, 5 PSID. Once the elements begin to get clogged, that number goes up. When they reach 15.0001 PSI differential, the bypass opens up so you do not blow out the elements. Some non-filtered oil is BYPASSING the elements.

From an engineering perspective, for Nissan to engineer a filter that can withstand 35.999 pounds of pressure per square inch before the bypass opens, that is pretty impressive. (Go to a gym, and try to hold up 35 pounds with your thumbpads side-by-side.) That amount of pressure would be felt on each and every SQUARE INCH of the INPUT SIDE of the filter if it is clogged before the bypass opens.

(So here is where my opinion and power of deduction comes in to play.) WHY would they select a stupid-high bypass filter pressure? Simple. They figured out the solenoid could get gummed up and fail OPEN, causing you to wipe your bearings when you go from a normal idle down the road to revving up quickly (And the solenoid not retracting super quickly). They figure if oil gets filtered, there's less crap that could gum up the solenoid shaft. Many of us have solved this issue by: Disconnecting the solenoid. Using 5w30 oil. Doing regular oil changes.

 

[2Cool]

I am using the GTR filter as well, along with a solenoid blockoff plate and 5W-30 Mobil 1 extended performance oil. The greater filter surface of the GTR filter is worth it to me, and I will be doing changes every 5K miles to make sure the internal bypass pressure differential never becomes an issue.

 

[Mugzilla]

I am using the GTR filter as well, along with a solenoid blockoff plate and 5W-30 Mobil 1 extended performance oil. The greater filter surface of the GTR filter is worth it to me, and I will be doing changes every 5K miles to make sure the internal bypass pressure differential never becomes an issue.

Bingo. Oil filter elements are corrugated (?) to give them more surface area. If they never get clogged, you'll never hit the bypass setting.

NOW, you and I are using 5w30. It is a thicker oil. Therefore, this oil will cause more differential pressure across the filter elements. Not a lot; but some.

Not enough for me to worry about though.

 

[Kludos]

Also in Aus running 5w40 and the solenoid delete and a GTR filter. I think many of us pushing our VR30s run this setup.

 

[Mitchb]

Bingo. Oil filter elements are corrugated (?) to give them more surface area. If they never get clogged, you'll never hit the bypass setting.

NOW, you and I are using 5w30. It is a thicker oil. Therefore, this oil will cause more differential pressure across the filter elements. Not a lot; but some.

Not enough for me to worry about though.

Intuitively, you would think a thicker oil would result in a higher differential pressure across the filter element, but this is not necessarily the case. Cold or thicker oil results in greater oil pressure because of the higher resistance to the oil flow across all the bearings and oil feeds throughout the engine. Test results on a standard v8 dyno engine measuring oil pressure both before the filter and after showed cold start differential pressure in the 2-3 psi range which grew to close to 10 PSI max when stabilized at operating temp and high RPM. I think 5W-30 was used. Unless the engine is using an extremely small filter with high flow rates imposed on it, thicker oil will not bring you into high diff pressures at the filter. Unless there are some mitigating circumstances out of the ordinary, the opposite will be true.