niteblues59 wrote:fmaxwell wrote:I would love to take credit for original thinking there, but deep the big diesel equipment manufacturers have long tied oil change interval to sump size; deeper sump means longer oil change interval. Caterpiller even lists two different change intervals for the exact same engine in the same equipment.
These ain't Caterpillar motors...or diesel.
I know. Ural engines are built by faeries and don't put combustion byproducts into their oil. They don't experience blow-by like any other air-cooled engine. The parts-per-million readings for contaminants is totally unrelated to the volume of oil. Oil analysis that can be done for all other gasoline and diesel engines is meaningless on our enchanted Ural engines. We change our oil because that magic spell that keeps it lubricating wears off.
Quaker State web site wrote:Oil changes are necessary, not so much because oil wears out, but chiefly to flush contaminates from the engine before they build up to dangerous concentrations.
Motor oil is changed, whether in a Caterpiller diesel engine, or a Ural engine, because it has become contaminated and degraded. If you have less oil, the contamination concentration is higher and it degrades quicker. This isn't some kind of weird new theory about engine oil. More oil (bigger sump size) means the oil stays fresher longer. Ford extended the oil change interval on the 2011 V-6 Mustang to 10,000 miles maximum by putting a 10 quart oil pan on it.
Question: why do you believe Ural crankcase oil is changed if not because of the concentration of contaminants, the increased acidity, or depletion of additive packages?