The article shown below will detail for you one of six incredibly valuable engine oil tests that you can use to quickly establish the continued viability of your oil, without ever sending it off to a lab.
It is best to rely on oil analysis to determine your oil change interval. Of course, on many passenger car vehicles that only take 4-6 quarts of oil, the price of the oil analysis is nearly as much as a complete oil change.
This is #2 from a series of six very useful, and low cost, oil analysis tests that you can perform without even a simple chemistry set.
