Originally Posted By: Danh
Originally Posted By: cptbarkey
"This is the only wear metal that accurately and linearly increases with the length of time the oil has been in service. It has many sources inside of an engine, most commonly coming from cylinder liners, camshaft lobes, crankshaft journals, and oil pumps."
I think this is building a case to trade that thing in. Sorry
What about the BITOG conventional wisdom that "A UOA is only useful for assessing the condition of the oil, not the condition of the engine"?
Disclaimer: I am not by any stretch an "experienced BITOG'er," but I'd call B-S to a
certain extent on this.
Yes - the UOA tells us (*SOME*) of what is in the used oil, some additives, wear metals and the remaining detergent if requested.
It can also tell us of the presence of coolant, fuel and/or silicon.
If the former two are present, then it wouldn't be out of line to suggest something may be very wrong with the engine, i.e. Head-gaskets/head cracks, excessive blow-by, very rich running.
Silicon tells us if there are filtration issues or air leaks introducing unmetered air in the engine, and thus inducing higher wear. On a modern engine - air leaks of this sort may cause a CEL or problematic idling/starting, so its not as if the owner/driver would be completely oblivious to this.
Obviously if the wear metals come back reading extraordinarily high - then either the testing equipment was bad OR something is causing excessive wear in the engine, and that is ending up in the oil.
All in all, I'd say the UOA is appropriate for determining issues like HG leaks, rich running (one should be able to smell this) or air leaks.
After that, major wearing issues. What it can't tell you is wear the wear is occurring specifically and whether or not its a problem NOW, or if the engine is very sturdy and will last another 100K!
The other thing I'd say is if the oil is jet-black after a short interval - well, it must be picking up something along the way, and the UOA can reveal whether whats happened to the oil with your engine is inline with their averages or not.
By the way - BITOG experts are free to correct me on ANY of this if I'm out of line. I read a lot of older posts here, and what is written above is, perhaps, something of a summation.
