Posted by Alan Bowes on February 28, 1999 at 10:25:14:
In Reply to: 230 ci oil filter system posted by Moby on February 27, 1999 at 14:11:26:
Well, if you change filter types, it's at your own risk. The 230 uses a "bypass" type filtration system and there is a small orifice in the stock oil filter center tube that proportionally limits the volume of oil that passes through the filter when the engine is cold and allows the temporary buildup of extra pressure in the oiling system to ensure prompt lubrication of the bearings. Without this orifice, the cold oil would tend to flood out of the relatively large pressure relief valve port before it has a chance to be forced into the narrow bearing clearances that have more resistance to flow. After the oil warms up and thins out, it flows more easily to and through the bearing clearances, and the orifice allows a greater proportion of the oil to pass through the filter element.
The function of this orfice may not be so critical with modern multiviscosity oils (especially synthetics) that flow more easily at low temperatures. HOWEVER, I certainly would NOT want to experiment on a newly rebuilt engine to find out whether this is indeed the case or not.
For a rebuilt engine, my advice is to stick with the stock oiling system, use a non-synthetic oil for the initial break-in period on a rebuilt engine, and then switch to synthetic oil. For more "tired" engines, I would only switch to a synthetic if the interior of the engine is quite clean, such as with an engine that has been fed a steady diet of detergent motor oil and run with a proper thermostat in place (which avoids sludge deposits). Change the filter regularly. The engine should last a LONG time if it was properly rebuilt and if it's maintained properly.
Have fun,
Alan