Originally Posted By: Pablo
Originally Posted By: Jeff_in_VABch
When you take identical engines, one with long OCIs and one with short OCIs, the one with short OCIs is going to produce more power, torque and efficiency, even though they may both run to 200K+ miles.
Prove it.
It appears you have very limited technical understanding of engine mechanics, which is understandable, as most of the public is not in a technical field.
I will give you a few examples which you should be able to understand.
The most common problem with Ford's 7.3 Direct Injection Turbo diesel is related to engine oil change interval and type of oil being used. It is critical for proper engine operation that the customer or technician servicing the vehicle check that the correct oil is being used. This engine uses a high pressure oil pump to operate the fuel injectors. Typical system pressures are 500 psi at idle, 1200 at 3300 rpm in neutral, and 3600 psi at full load acceleration. Oil for the PowerStroke requires an anti-foaming agent to prevent the oil from aerating and reducing pressure, which would result in poor fuel injector spray patterns and reduced power. Depending on vehicle usage, the anti-foaming agents are depleted in 3000-5000 miles.
Approximately 60% of engine wear is achieved by means which do not produce material loss and therefore do not show up in used oil analysis as additional materials/analytes in the oil. Burnishing (plastic type deformation) and peening (another plastic type deformation) are just two modes of wear in an engine which have significant effects on components.
Burnishing occurs on surfaces that conform to each other, such as between the ring and cylinder wall or timimg chain pin and roller, but it happens on a microscopic scale. Even the smoothest of surfaces will have imperfections if viewed at a high enough magnification. The imperfections that extend above the general form of a surface are called asperities, and they plow material on their mating surface. The combined effect of many of these asperities produce the smeared texture that is associated with burnishing (which appears to be a polished surface). This burnishing effect is always bad. Modern cylinder bores recieve a 3-step cylinder bore finish preparation. This preparation provides a microscopicaly rough bore with a plateau finish. Any material deposition in the valleys of this finish (oil deposits or burnishing) significantly reduce piston ring sealing and lubrication while while producing little to no change in bore diameter.
I dont have time to keep on this thread, but similar burnishing processes causes lengthening of timing chains which retards cam timing and reduces cylinder pressure and effective power over time.
Also, the peening wear process affects components in the valve train, including the cam lobes which reduces overall valve lift and significantly reduces power.
There are lots of other wear processes going on that the UOA does not account for. Im just saying, you can run that old oil as long as you want, and it will probably run forever, but you are still wearing out thousands of contact points at an accelerated rate and reducing performance.
