Used oil analysis only tells part of the story. The insolubility in a very old oil is clear. The additives percipate and coagulate at the bottom of the bottle. A good fresh oil needs no shaking or whatever because everything is stable and soluble. The molecules of the oil hold everything in suspension.
The fact that manufacturers only guarantee the good age of oil is 5 years for scientific reasons. The additives consist of organometallic compounds, and over time they degrade. However, 5 years is just a recommended best-case scenario if the oil is stored properly in a sealed container. 1 year old oil in the engine just sitting may not be as good as 3 years old oil in the bottle.
Project Farm did a quick UOA on 1 year old oil in the engine sum, and they are still good, including the oxidation level. I think a 2-year-old oil change is ok for Diesel with good oil or gasoline cars that just sit without too many cold short trips. Especially cars that are driven only during summertime when there is no ice on the road. I won't use it longer than 2y.
I still believe my daily commuter cars should have a 6-month/5k mile oil change interval with whatever API SP or ACEA C5 discounted oil from local stores (Advanced, Autozone, ORelly, etc.).
The fact that manufacturers only guarantee the good age of oil is 5 years for scientific reasons. The additives consist of organometallic compounds, and over time they degrade. However, 5 years is just a recommended best-case scenario if the oil is stored properly in a sealed container. 1 year old oil in the engine just sitting may not be as good as 3 years old oil in the bottle.
Project Farm did a quick UOA on 1 year old oil in the engine sum, and they are still good, including the oxidation level. I think a 2-year-old oil change is ok for Diesel with good oil or gasoline cars that just sit without too many cold short trips. Especially cars that are driven only during summertime when there is no ice on the road. I won't use it longer than 2y.
I still believe my daily commuter cars should have a 6-month/5k mile oil change interval with whatever API SP or ACEA C5 discounted oil from local stores (Advanced, Autozone, ORelly, etc.).
