Application of Qualitative Filter Paper on Engine Oil Detection

For some vehicles, especially the ones beyond the warranty period, lots of owners prefer to decide the oil change cycle by themselves. The qualitative filter paper test method is a simple way for people to determine a reasonable oil change interval of the oil.

Testing Method

First of all, make sure that the temperature of the engine oil is as high as the outside temperature. And then use an oil dipstick to extract the oil and drop it 1-2 drops in the middle of a piece of qualitative filter paper. Next, the filter paper should be put on an empty container (cup) horizontally. The last step is to leave it for 24-48 hours and then to observe the oil spot and judge the oil life.

Wet Strengthened Grade Filter Paper
Medium Flow Filter Papers
Cellulose Filter Papers

Result Analysis

There are mainly three annular areas shown on the filter paper in the test result, including diffusion ring (the center circle spot), deposition ring (the one next to diffusion ring), and oil ring (the peripheral ring of the deposition ring).

If there is no obvious boundary between the diffusion ring and deposition ring and their color is uniformly distributed, it means the engine oil is good enough to continuously used.

If the color of the deposition ring is deeper and the diffusion ring is wider while the oil ring is in different shades of yellow, that indicates the oil has been contaminated yet still usable. If the deposition ring is in deep dark with dense sediments and the diffusion ring is narrower while the color of the oil ring is deeper, or there is no longer a diffusion ring, it means the engine oil has to be changed.