Cheap Motor Oil Analysis Tests: The Blotting Paper Test
It’s often hard to know for sure how long your oil might last before needing a change. The type of car you drive, the size of the engine, the age of the engine, the type of driving you do, and the type of oil that is in your pan will ALL have a significant effect on the longevity of the oil.
Of course fast lubes will keep telling you that 3,000 mile changes are a must and for SOME people this may be true. However, for the vast majority of us, this has not been necessary for many years. Unfortunately, determining HOW LONG is okay can be difficult.
Enter oil analysis
The best way to establish realistic oil change intervals is through oil analysis. Those who have been professionally trained to test oil and have expensive laboratory equipment at their disposal are best qualified to determine the quality of used oil found in your vehicle.
However, such a thorough analysis of your oil can be cost prohibitive, as a professional oil analysis can often cost as much as a 5-quart petroleum oil change.
The result: we don’t
Of course, the upshot is that most people won’t pay for a “true” oil analysis, but might be willing to do a simple oil analysis themselves, if they knew how to do it. It won’t give you detailed numbers like you’d get from a lab, but it can give you a pretty good idea of how well your oil is holding up, helping you decide whether or not it’s time to make a change. .
Below you’ll find detailed instructions for 1 of 6 simple oil analysis tests you can use to determine how well your oil is holding up and whether it’s ready for a change. This way, you can begin to set realistic oil change intervals for your vehicle.
Carrying out the test
Using this simple layman’s oil analysis test can shed light on a wide range of potential oil problems that could require an oil change: excessive particles, condensation buildup, glycol contamination, fuel dilution, engine failure, dispersing additives, sludge formation and oxidation. It’s probably one of the most useful DIY oil analysis tests you can perform, and it’s very simple.
While your engine (and oil) is HOT (not HOT), drop a drop of oil from your dipstick onto a heavy, white, NOT shiny business card. Lay the paper or business card flat, but so that all but the edges of the paper are suspended. As a possible example, if you’re using stiff cardstock or a stiff business card (which it really should be), simply place the card on top of a cup or mug of some sort.
You want to wait for the oil drop to be fully absorbed by the paper or card, which can take a while. The list of characteristics below should help you assess the condition of your oil based on the DRY oil stain.
- If your oil is still good for continued use, the dried oil stain will be an even color with no particularly dark areas or rings. There may be a slightly yellow outer ring.
- If your dispersant additives are failing, you will probably see a very dense and quite dark area, usually within the center of the circle. Consider changing your oil soon, especially if other problems arise in the course of the “trial.”
- Glycol (antifreeze) in your oil? Expect to see a very black, somewhat “pasty” area within the oil slick. Change your oil very soon.
- If the circle is very dark and has a very distinct outer ring, the oil is badly oxidized and should be changed immediately.
- If the center of the circle is quite dark and there are outer rings, it is likely that there is fuel in the oil. This doesn’t necessarily mean you need to change the oil, as it’s common for there to be fuel in the oil, but it might if the level is too high. Only a professional analysis will tell you how high those levels are.
