Originally Posted by Talent_Keyhole
Originally Posted by CourierDriver
I know oil analysis is a big deal, but I have never lost an engine do to oil ....
Catastrophic, sudden, mechanic engine failures are rarely identified beforehand by oil analysis and normally not caused by oil. In that sense I agree. Have engines experienced shortened life span, severe wear from wrong viscosity, over-filling, poor quality oil, severe contamination, sure. Most people do not keep their vehicles long enough for an engine failure or be able to ascertain a shortened life span. There have been a few cases where junk oil (API SA) and even used oil has been re-bottled and sold on the market. In those cases damage was caused by the oil alone.
I, too, have never lost an engine due to oil failure, or a filter failure for that matter.
But that does not stop me from doing UOAs. Because UOAs have more than one purpose.
UOAs can, but will not always, predict a component failure. There a lot of "what if ..." scenarios here; too many to make a blanket statement other than to say UOAs can see some instances of imminent failure, but not all.
UOAs are first and foremost a fiscal savings too, although you'd not really know it given how BITOGer use them as toys. UOAs are most effective at deciphering wear trends, and then using that knowledge to set reasonable OCI cycles. If the UOA shows good wear, low contamination and decent physical properties, then you should extend the OCIs out. You do that in a continued fashion until you reach some condemnation point. Why do an OCI at 5k miles if all is good at 10k miles? Why OCI at 10k miles if all is good at 15k miles? In large sump systems, you can often see OCIs go 30k to 100k miles (typically in OTR trucks).
There is a caveat; UOAs can cost as much or more than an OFCI at times, so the ROI really isn't great, especially on small sump systems. Why pay $32 for a UOA for you 2-qrt riding mower? Why pay $28 for a UOA when $25 will fill your sump? In these circumstances, I advocate for UOAs to establish a mantra, then cease the UOAs until an issue is suspected. For example, I used UOA data to prove that 10k mile OFCIs are safe for our 4.6L Ford engines; the data repeatedly shows no ill effects. After establishing the safe trend, I then stopped the UOAs. I will only get another UOA if I see something go awry; smell of fuel in the oil, appearance of coolant in the oil, audible noises that would indicate mechanical issues, etc.
PCs are also a tool. They have benefits, but also limitations. They help you understand particulate loading, but they don't speak a word to the substances found. PCs tell you about loading, but UOAs tell you about elements. PCs will tell you how large something is, in a delineated scale of concentration. UOAs will tell you the composition of the element, but not size.
The better way to manage a maintenance program is to use the tools (PCs, UOAs, physical observations) together, and understand the pros/cons of each tool used in concert with each other.
