Why oil additives turn to an acid?

Why oil additives turn to an acid? 27 november |

27 november

Not so far ago, one of the popular YouTube bloggers, Denis Legostaev, has published a curious test of oil additives, in which he measured acidity by heating them with a construction heater. We decided to repeat the test at operating temperatures and to check whether the most popular additives are stable and safe for motor oil.

In our test, there were 10 samples: popular additives in Russia and one original sample, brought by our colleagues from abroad. We will heat additives to 100-120°C and monitor their acidity.

    The test samples were assigned with
    sequential numbers

  1. iMagnet P14 – HTHS-Viscosity Stabilizer
  2. Resurs NEXT – remetallizer
  3. Bardahl Full Metall – complex additive
  4. ER – metal conditioner
  5. STP – Smoke Treatment – conditioner
  6. Suprotec Active Plus – geomodifier
  7. LM Visco Stabil – Viscosity Stabilizer
  8. SMT – metal conditioner
  9. ABRO – oil thickener
  10. Modifikator Plus Stiba – friction modifier (Serbia)

The main indicator in our experiment - litmus paper - is the fastest and observable way of check the acidity. Upon contact with acid, the paper is colored by bright pink color.

Look at the photo below. In the right glass is acid, in the left - neutral pH water. Note how the acid affects the valve metal spring.

It instantly starts the process of chemical corrosion and literally eats the metal. Thus, every time the litmus paper in our test is painted in shades of pink, this will indicate the presence of acid.

Neutral (water) ACID

We poured 15 ml of the additive into a test tube, fixed the litmus paper inside and sealed the container. 


To create equal temperature conditions, we decided to heat the additives simultaneously, by placing them in a common tank.

After 3 hours, the additive reached the working temperature range.

Are you interested in what happened next? We will definitely share with you. But first, let us explain why this issue with acid is so important for us.

Do you know why sludge and carbon deposits on the pistons are formed in such quantities?

Because during operation, engine oil, like any substance, is oxidizing. Washing additives (including a large number of alkaline additives), designed to protect the engine from deposits, first successfully neutralize the acids, but eventually, they exhaust their resource. The acid number begins to grow in uncontrolled manner. Sludge deposits no longer meet resistance and are safely deposited on piston rings and oil channels. That is why it is extremely important for additives to be neutral to the oil. Or at least, did not increase it's acid number.

You could not even imagine what the oil turns into without detergents

Additives that emit acid in motor oil are unconditionally harmful and unsafe for the engine. There is a whole class of "acidic" additives - metal conditioners, called by manufacturers as a "friction winners". They perfectly perform antifriction functions, while completely destroy detergents.

What about acidity?

But back to our test. After three hours we got results. Only 2 out of 10 litmus papers were painted in a rich pink color.

Samples #4 and #8 did not pass the acidity test and became the antiliders of our testing. Only their indicators recorded the presence of acid.

4. ER - metal conditioner 8. SMT - metal conditioner

These are popular oil additives and the only ones metal conditioners in our experiment. According to tests placed in public sources, they demonstrate phenomenal antifriction results, improving the oil index by 3-3.5 times. However, from the test to test, they lose in safety. And for that reason, metal conditioners are banned for use in many Western countries. They shorten the life of the oil, motor, and pollute the environment with acid vapor.

We see that regardless of the manufacturer, each of the metal conditioners demonstrates a negative effect on the alkaline environment, and at the same time on the detergent alkaline additives. The remaining participants retained a neutral acidic range. We can conclude that at operating temperatures, most of them do not affect the growth of the acid number and in this sense are safe for the engine.


And the conclusion. The so-called winners of friction win not only friction in the engine, but also detergent additives in oil, lead to the deposition of sludge. Their use is unsafe for both the engine and for the engine as a whole.

We couldn't say that all non-cinditioners additives are safe. For this kind of conclusion, our simple experiment is not enough, because there are a dozen factors of influence. However, choosing an additive only for "the car will be better" is not right and we can seriously "burn" by the acid of synthetic metal conditioners.

Remember this, and your engine will be thankful.

In our next article, we'll talk about the impact of iMagnet P14 and RESURS Next on engine cleanliness.

It is interesting!

We held a popular vote. The participants had to guess which additive would release the acid:

  • iMagnet P14 – 11,9%
  • Resurs Universal – 9,1%
  • Bardahl Full Metall – 7,7%
  • ER* - 10,5%
  • STP – Smoke Treatment – 3,5%
  • Suprotec Active Plus – 23,8%
  • LM Visco Stabil – 8,4%
  • SMT* – 9,1%
  • ABRO – 9,1%
  • Modifikator Plus Stiba – 7%

Only 19.6% of respondents answered correctly and chosed the conditioners (in the list marked *), as the carrier of the acid. While the majority of motorists choosed the additives guided by their likes and dislikes of the brands.

The voting data at 11/23/2017

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