Originally Posted By: rg200amp
Originally Posted By: OVERK1LL
Originally Posted By: demarpaint
If the higher Fe #'s generally found with Mobil 1 UOA's are not from wear what are they from? If its something in their mfg or packaging process and iron is harmful to an engine then why not remove it before bottling the product? Granted I'm no expert on UOA's. Maybe they can't determine how much an engine is wearing, still it is a number that a lot of people who do know how to read them seem to always point out. Pablo is correct in saying Mobil 1 seems to be in the middle of the pack, and for the price they charge they should be a leader of the pack in quality, not volume. To all members: Spend your money anyway you like after all it's your money.
UOA's sample a NARROW spectrum of particulate size. It is very possible that the average Fe wear produced by this particular grade of oil is simply higher within that size-range and lower outside. We do not know. We also do not know if other oils have HIGHER Fe wear outside of this spectrum and lower within. They are NOT a tool designed to evaluate wear!
This is why tear-down testing is performed. To evaluate wear. BuickGN had some great UOA's and some horrible wear. So what did the UOA's tell him? NOTHING other than his oil didn't have coolant in it
My understanding of what a UOA provides, based on Doug's results is this:
AVERAGE oil contamination in terms of wear metals, fuel dilution, ash load and other items that can indicate external contamination sources like coolant leaks. It gives you a useful indication of remaining oil life and how easy or hard the engine is on oil.
Great tool to use to determine your maximum OCI or if you have fuel dilution or coolant problems.
Not a great tool to determine how your engine is wearing.
Yes, but a new car shows high wear numbers on a UOA, and a broken in car with quality oil and good OCI shows good wear numbers on UOAs.
When theres an issue like alot of dirt getting in the oil like SI, wear numbers go up. SO yes a tear down is the best way. But I do think a UOA can tell something. Even if it only shows a "NARROW spectrum of particulate size" I would want that spectrum along with rest of it at its lowest point. So if that one spectrum is low, I would trust so is the rest.
TO my understanding, the bigger Iron particals can not be seen in a UOA. SO if the smaller partical count is lower with one oil, I would trust the larger particals that are not shown on a UOA would be lower as well.
Because the NARROW spectrum sample is considered representative of the AVERAGE degree of contamination.
The thing is, it is possible that there are fewer larger particles generated by the M1 5w30 and simply a higher "signature" within the range that happens to coincide with what is sampled in the UOA, giving you a false "high", when none exists. Whereas another oil has more wear over a broader range, but the sampled range would show less contamination.
This is why an actual tear-down with REAL measurements is the best means of evaluation. Because we really DO NOT KNOW. It is all speculation.
Now Doug actually provided REAL evidence, using 150ppm of iron as his condemnation limit on his UOA's, and did a tear down at 1.2 million Km to find no real wear! The engine was reassembled and is STILL in service now with something like 2.5 million Km on it.
So what exactly did that 150ppm of Fe in the UOA tell him other than a contamination level?
