Originally Posted by Pairajays
Annual oil changes, without substantial milage, is not required, IMO.
Is this true in diesels? As an airplane mechanic, I stress annual oil changes as the very least; six months is often preferable. The reason is that your oil protects in two ways: mechanically, by definition; and, chemically by maintaining a protective coating on surfaces inside your engine. With the introduction of moisture, acids form, the protective role is compromised, and engine life is shortened.
Cummins, in their bulletin entitled Cummins® Engine Oil and Oil Analysis Recommendations
, says the same thing: Oil provides a protective barrier, isolating non-like metals to prevent corrosion. Corrosion, like wear, results in the removal of metal from engine parts. Corrosion works like a slow acting wear mechanism.
These are the engineers who built your engines, who gain nothing if you shorten your oil change interval. But, they don't quantify the amount of wear nor do they address environmental variables.
Now, in jumps the State of California, which says you can optimize wear by using premium oil and high efficiency filters, coupled with extended change intervals. Their findings are HERE
. Does the same thing apply in Ohio, Florida or Michigan? I have no idea.
What do our professional diesel mechanics think?