Posted by Steve Kaminsky on October 20, 2003 at 12:16:22:
In Reply to: oil pressure posted by Fred on 13:13:29 10/19/03:
Acceptable oil pressure on an Atomic 4 ranges from 20 lbs at idle (~750 RPM) to ~ 40 lbs at crusing speed (1850 - 2100 RPM).
Following is an excerpt from a an e-mail conversation I had with a freind and fellow Atomic 4 owner regarding oil pressure:
"First, I should explain that on our A4 I have installed the Indigo Electronics Oil Filter & Oil Cooling Kits and that I used synthetic oil exclusively.
The Oil Filter Kit has its own "Precision machined Pressure Regulating Valve with broader regulation for more constant oil pressure", according to Indigo's website. In practice, my pressure varies during engine operation from 38 to 42 lbs. regardless of engine temperature or RPM. That's according to the direct reading gauge on the engine, and the control panel
gauge which follows to those readings fairly closely.
If you are using a straight 30 weight oil in your A4, I would expect to see higher pressure at start up - due to the lower temperature, and as the engine warms up - lower pressure, as the oil begins to thin from the temperature. Use of a multi-grade oil should help reduce this somewhat.
In a perfect world, the oil pressure regulation valve on the engine should be able to adjust the pressure to compensate for the change in oil viscosity and engine RPM (within reason) and maintain a fairly constant oil pressure throughout the system. In the real world, the A4's pressure regulation valve is not that sophisticated (no insult intended) and has several areas which can cause problems: the valve, the valve seat, and valve spring
integrity (the spring can become fatigued); and as you mentioned, the condition of the bearings will also have a direct effect."
I hope this helps.