Conventional oil is now so good there is little reaon to go synthetic in most applications.
But a 5 quart bottle of pennzoil yellow bottle being 18 dollars and a 5 quart jug of Mobil one being 3$ more at wal mart. well spread out over the year to 18 months I keep my oil in circulation, is insignificant. Sure some 5 quart jugs can goto 12$. so 9 dollars spread out over a year. Big whoop.
Over on the Bitog forums is is generally accepted that used oil analysis is not a report on Engine wear, but how the oil is holding up in that particular service interval in that particular engine. Some oils do not hold up very well in some engines where other oils certainly do.
Oils can shear to a lighter viscosity, they can be diluted with fuel, or contaminated with antifreeze. Their total base number declines with time in the sump, and some oild TBNs start higher and decline slower than others.
Oil is not just oil, but the differences in engine wear from one engine to another conventional vs synthetic, well it would be extremely difficult to quantify in a scientific matter with all the variables removed.
Most people go by their butt dyno. I can hear slight differences in engine noise with different oils. The quieter oils give me warm and fuzzies. I bet a used oil analysis would show the wear metals of iron, aluinum lead tin copper, to be all similar comparing the louder and quieter oils and signify next to nothing.
I had one oil sample analyzed. there was coolant present showing up as sodium and Potassium. i had hoped the timing cover/ water pump was leaking only to the exterior, but the analysis proved It was geting inside too. Wear metals were not elevated to the point where they were a concern. TBN(acidity fighting ability) was still high, viscosity exactly in range, no fuel present, flashpoint as expected. That was A 13 month service interval. Even with the coolant contamination the oil was good for at least 6 more months.
People will read see and think exactly what they want to think and believe either way.
If your engine is still under warranty, make sure the oil used is certified for use in that engine, and keep the receipts, even though the chances af ever having to present them are comically low if a normal oil change interval is kept.
