Originally Posted By: TFB1
Originally Posted By: Astro14
Combustion byproducts and other forms of contaminants enter the oil via various means. The oil is leaving your engine by being burned...Those contaminants are not leaving your engine by being burned and will circulate in the oil until it is drained.
Find the cause of your burning/leaking and fix it....and continue to change your oil. OCI and type are up to you...but change it...
I disagree, most of the contaminants will be suspended in the oil and will go wherever the oil flows... True the contaminants will build, but it will be to a average point that will be reduced each time oil is added, then they will build to approx same average high when level becomes low...
Hmmm...OK, If it were leaking out, I would buy the contaminants going with it, drop by drop...
But he's burning, not leaking, one QT every 1,500 miles...and your contention is that the same thing happens to the oil when it's being burned...that, on a very fine scale, as literally molecules get past the rings or valve guides, that the additives and contaminants in suspension go with the oil on the same path? Including particulates? And that the contamination will build to a roughly steady-state that goes up slightly as oil is burned and down slightly as it is added?
OK, so let's take that as the way it happens...then, the question becomes: is that steady state level of contamination above or below the oil's ability to handle it? Put another way: does the oil settle to a steady state of contamination with a TBN above 1.0 (acceptable) or below 1.0 (unacceptable)? There are more factors here than just burn/replace rate...in an engine with this high mileage, there is the rate of contamination to consider as well...
I would think that only a UOA would give you the true answer for the oil's health at its steady-state...but changing it would ensure that it remains within the acceptable range of contamination...