Motor oil test

Engine oil quality affects normal engine operation, engine life, fuel consumption, vehicle performance, and the amount of lubricant that goes to waste. The sophisticated chemical analysis allows you to know in detail the composition of the oil and decide whether it needs to be changed or even whether the engine needs to be repaired. However, the most important indicators, such as the presence of metal chips, soot, fuel or liquids in the oil, can be checked for free on your own.

How much does it cost to have engine oil analyzed?

The cost of an oil test kit ranges from $25 to $50. The test will take two to four days and the results will show a lot of useful information about internal wear and contamination, changes in chemical composition and physical properties. Most changes in chemical composition lead to physical changes. These can be identified by paper chromatography. And to do such a drip test you will need about half an hour (but more accurate results appear after 24 hours) and a blank sheet of A4 paper (will cost nothing) or a few packaged one-drop test kits designed for field-testing oil, which will cost $15-$20 ($20 for a six-sample kit, and a refill is $15). Both methods allow you to quickly find out the condition of your oil and engine at home.

If you regularly use the drip method every 3,000 miles (saving the results), you can track changes in the condition of both the oil and the engine itself.

How do you check motor oil at home?

The easiest way to How to Perform Oil Analysis and see if your engine parts are critically worn is to take 30 grams of oil from your engine and put a magnet in it. If there's metal dust on it it's worth not just changing the oil but a more thorough check of the engine.

Lube Oil Tests Drop Test Viscosity Test Water Content Test: video

The second way to check the presence of foreign impurities is to drop a couple of drops on a small piece of glass and rub it over the surface with the second piece. If during rubbing you hear a metallic squeak or crunch, and moreover you feel the mechanical impurities, it means that there are chips or the oil filter is worn (it can't filter).

Another simple test is to put a sheet of clean paper at an angle of 30° to 45° and drop a couple of drops of the oil being tested on it. Part of it will be absorbed into the paper, and the rest will spread on the paper surface. This is the trace that you should look at closely.

The oil should not be very thick and extremely dark (like oil). There should not be small black dots in the trace, which are metal domes. There should also be no individual dark spots, the oil trace should be uniform.

If the oil is dark in color, but still fairly fluid and clean — then it is probably still usable, and it is quite good quality.

How You Can Check if the Oil Has Lost Viscosity

To check if the oil has lost its viscosity, you can use two methods.

The first one is to take some of the old oil and the rest of the fresh one from the canister (if you changed it yourself and have the possibility). Pour into the tubes, close the stoppers and place both at the same time at a slight angle. Then watch and compare how fast the samples flow. And you can test both heated oil (to the same temperature) and freezing it (by placing it in the freezer). It is primitive, but even such testing will be enough to determine if the oil in the engine became more liquid or became bitumen because it was not changed for a long time, but only added to.

For the second way to see at home the viscosity changes of the oil working in the engine you need a vessel with a thin neck (1 — 2 mm). For this purpose you must take equal amount of new oil (with the same declared viscosity) and lubricating fluid from the crankcase. And pour into a dry funnel or other vessel on the second end of which there is a thin hole each oil one by one. Using a stopwatch, you can easily calculate how many drops of one and the other oil will drip in the same time interval.

If these values are very different — it is advisable to change the oil in the crankcase. However, a decision to do so should also be made on the basis of other analytical data. An indirect confirmation of bad oil is its burning smell. Especially if it contains a lot of impurities, the presence of which can be determined by an engine oil drop test.

Oil Drop Sampling

Example of a drip test

The one-drop method is a very simple process, accessible to anybody under field conditions. It was invented by SHELL in 1948 in the USA, and can be used to quickly check the condition of oil with just one drop. The droplet test not only reveals the quality of the engine oil, but it also tests the following parameters:

  • condition of rubber gaskets and seals in the engine;
  • properties of the engine oil;
  • condition of the engine as a whole (in particular, whether it needs an overhaul);
  • determine when you need to change the oil in the engine of your car.

How to Do an Engine Oil Analysis on a drop test?

To do this you need to act according to the following algorithm:

  1. Warm up the engine to operating temperature (you can about +50...+60°C, so as not to get burned while taking the sample).
  2. Prepare in advance a clean white sheet of paper (its size does not matter much, a standard sheet of A4 paper folded in two or four layers will do).
  3. Open the crankcase filler cap, and with the help of a dipstick put one or two drops on a sheet of paper (at the same time you can check the level of engine oil in the engine).
  4. Wait for 15...20 minutes so that the oil is properly absorbed into the paper.

The assessment of engine oil quality is made by the form and appearance of the resulting oil spot.

What does oil analysis by the type of smudge tell you?

The first thing to pay attention to is the color of the individual four zones formed within the boundaries of the slick.

  1. The central part of the slick is the most important! If the oil is of poor quality, it usually contains soot particles and mechanical impurities. For natural reasons, these cannot be absorbed into the paper. As a rule, the central part of the stain is darker than the rest.
  2. The second part is the oil stain itself. That is the oil that has been absorbed into the paper and has no additional mechanical impurities. The darker the oil, the older it is. However, additional parameters are needed for a final decision. Diesel engines will have darker oil. Also, if the diesel is heavily «smoky», there is often no boundary between the first and second zone in the droplet sample, that is, the color changes smoothly.
  3. The third zone, far from the center, is represented by water. Its presence in the oil is undesirable, but not critical. If there is no water, the edges of the zone will be flat, close to the circumference. If there is water, the edges will be more zigzagging. Water in the oil can have two origins — condensate and coolant. The first case is not so bad. If glycol-based antifreeze got into the oil, there will be a yellow ring, the so-called corona, on top of the zig-zag border. If there are a lot of mechanical deposits in the oil, soot, dirt and impurities can be not only in the first, but also in the second and even the third circular zone.
  4. The fourth zone is represented by the presence of fuel in the oil. Therefore, in faultless engines this zone should not be present or it will be minimal. If the fourth zone is present, however, it is necessary to revise the engine. The larger the diameter of the fourth zone, the more fuel in the oil, and therefore the more the car owner should be concerned.

Sometimes an additional test is performed to assess the presence of water in the oil. So, for this purpose the paper is burned. When the third zone burns, a characteristic crackling sound is heard, similar to a similar crackling sound when burning raw wood. The presence of even a small amount of water in the oil can lead to the following unpleasant consequences:

  • Deterioration of the oil's protective properties. This is due to the rapid wear of detergent and dispersant additives in contact with water, which in turn leads to increased wear of piston parts and accelerates engine contamination.
  • Contaminating particles increase in size, thereby clogging oil passages. This negatively affects engine lubrication.
  • Hydrodynamics of lubrication of bearings is increased, and it negatively affects them.
  • The freezing temperature (freezing) of oil in the engine increases.
  • The viscosity of the oil in the engine changes, it becomes greasier, though only slightly.

With the drop method, you can also find out how good the oil's dispersing properties are (the ability to hold in all the dirt). This index is expressed in conventional units and is calculated according to the following formula: Ds = 1 — (d2/d3)², where d2 is the diameter of the second oil spot zone and d3 is the third. It is better to measure in millimeters for convenience.

Oil is considered to have satisfactory dispersing properties if the value of ds is not less than 0,3. Otherwise, the oil should be urgently replaced with a better (fresh) lubricating oil.

Engine oil test results


MeaningDecipheringOperating recommendations
1, 2, 3Oil is free of dust, dirt and metal particles or contains them in small amountsEngine operation is permitted
4, 5, 6Oil contains a moderate amount of dust, dirt and metal particlesEngine operation with periodic oil quality checks is permitted
7, 8, 9Presence of insoluble mechanical impurities in oil is above normEngine operation is not recommended

Remember that changes in color one way or the other do not always indicate a change in the characteristics of the oil. We've already mentioned the rapid blackening. However, if your car is equipped with a gas turbocharger, on the contrary, the oil may not turn black for a long time and even have more or less light shade, even with significant mileage of the car. But it does not mean that it can be used forever. The thing is that flammable gases (methane, propane, butane) naturally have fewer additional mechanical impurities that contaminate the oil. Therefore, even if the oil in a car with HBO doesn't get significantly darker, you still need to change it according to the schedule.

Portable Pocket Oil Analyzer

Modern technical capabilities allow you to determine oil quality not only «by eye» or by using the drop test described above, but also with the help of additional hardware. In particular, we are talking about portable (pocket) oil analyzers.

In general terms, the procedure of working with them consists in putting a small amount of lubricating liquid on the sensor of the device, and the analyzer itself, with the help of built-in software, will determine how good or bad its composition is. Of course, it will not be able to perform full chemical analysis and give detailed information about these or those characteristics but to get a general picture of the condition of the engine oil for the driver the presented information is quite enough. For example, popular Lubrichek simply show in points (for example, on a 10-mark scale) the quality of tested engine oil. It is enough for an ordinary motorist to help to make the decision on the necessity of oil replacement.

A modern device, which is an interferometer (works on the physical principle of interference), can determine the following oil indicators:

  • amount of soot;
  • degree of oxidation;
  • degree of nitriding;
  • degree of sulfation;
  • phosphorous EP additives;
  • water content;
  • glycol (antifreeze) content;
  • content of diesel fuel;
  • gasoline content;
  • total acid number;
  • Total acid number; Total alkaline number;
  • viscosity index (viscosity index).

Knowing such indicators, you can not only determine whether the oil in the engine is already worth changing, but also whether it needs additional diagnostics for the presence of malfunction.

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