Originally posted by synskeptic:
From what I have read on this board, I get the impression that there is just no lubricant (mineral or synthetic) that, when used in an auto engine over time, will not degrade because of shear. Is my crude understanding of this correct?
No , the better oils will eventualy thicken but never shear below what they started as .
Oils degrade from combustion particulates and other reasons . The USA is far behind the Europeans in that they have been running longer drains for a period of time and actually sells concentrated top off oils for such drain up to 50k kilometers .
Typically across the pond these engines see no more than 3-4 oil changes in their lifecycle currently when maintained in this way .
Not a bad way to do it in a throw away world .
Now some cars are meant to be keepers from the start , maintenance should be adjusted accordingly for those types