What Oil Should I Use On Two-Stroke Motors – Synthetic Or Mineral?

For several years now, as many owners of two-stroke engines continue to argue about what oil should be used on two-stroke engines, old and new, synthetic or mineral. Let’s try to figure it out.

First, a couple of examples from life. One acquaintance, having bought a new foreign-made motor, stubbornly fed him the "MS-20", drawing on the extensive experience in operating Soviet-made motors. Well, gasoline used the AI-95. The motor lived without problems for two seasons, but the third began to malfunction. After some operations to adjust the carburetor, the ignition system and replace the candles, this bright husband nevertheless decided to “open” the engine. It showed that the combustion chamber was literally clogged with soot, and the rings, as they say, “lay down”. All this was implied before the showdown, but I wanted to make sure and convince the owner. The main problem of the owner, who almost killed the engine (after resuscitation the engine continues to live today), was that he used the recommended gasoline of the Ai-95 brand, but, without understanding the oil tips, he decided to take the best of what he knew.

Here is another example. Let’s say someone who has good water-motor experience, once decided that he no longer wants to communicate with domestic engines and, naturally, bought a “foreign car” for which he had been choosing oil for two-stroke engines for a long time. For some reason, this person did not want to buy “previously dissolved” oil, which can be simply poured into a can of gasoline in the right proportion, shaken and consumed as intended. To the question: “Why?” The answer was: "I do not trust, because it does not lubricate the elements of the motor well, because it has already been dissolved."

I hope so far there are enough examples from the life of domestic elders. Back to mineral water and synthetics.

So what is the difference between mineral oil and synthetic oil, with the exception of the retail price?

Differences at the core. That is, the composition of the additives in them may be identical, but the basis is different. Roughly speaking, it does not go into chemistry in mineral oil — from oil, but in synthetic oil — from specially obtained chemical elements, which chemists call olefin polymers, esters, ethers, alcohols, etc. Different manufacturers use different formulations and bases. Oils for two-stroke engines, which are based on up to 30% of the synthetic component, are produced by many companies. At the same time on their packaging can be written "Synthetic". On the one hand, this is a marketing move and an indication that the oil does have a synthetic component, on the other hand, this inscription can often mean that the flash point of the oil and its lubricating properties are improved compared to “purely mineral” oil. In the oil on the packaging of which there is the inscription “Fully Synthetic”, most likely, the synthetic base is 100%. Sometimes manufacturers are cunning by mixing a certain amount of mineral. True, this does not affect the quality of the oil very much, unless its biodegradability becomes slightly lower and a little more harmful emissions are formed. But it’s still a shame. you pay for 100 percent synthetic oil, but you get, for example, 92 or 89 percent.

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Video: What Oil Should I Use On Two-Stroke Motors. Synthetic Or Mineral?


Fully synthetic two-stroke engine oil, that is, 100% consisting of olefins and other elements, appeared on two main occasions: due to the requirements of environmentalists and the birth of powerful and heavily loaded engines, in particular, with direct fuel injection systems. Powerful modern two-stroke engines require oil, which, firstly, has good fluidity, which is important for successful operation in the Automix systems, and secondly, it is able to lubricate the motor elements well and at the same time quickly and completely burn out and, finally, thirdly, quickly decompose in the open air and be as less harmful to microorganisms as possible. The synthetic base of the oil makes it possible to satisfy the above requirements, although not completely, but more successfully than the mineral one, which has only a part of the mineral base. the so-called “semi-synthetics”. In a word, synthetic-based oil is more stable and convenient.

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Today, slowly, all oil producers are "going into synthetics", at least those who make oils for engine manufacturers. Oil is becoming more expensive, and the technology for producing olefins and analogues, if not getting cheaper, remains at the same level. However, in retail so far, “synthetics” remains more expensive than “mineral water”.

It turns out the following picture: new varieties of oils are automatically better than before. Of course, in their niches. At the same time, the “upstream” principle works, that is, completely synthetic oil can be relatively painlessly poured into the old engine, and oil intended for “classic” two-stroke engines cannot be poured into the new two-stroke engine with injection.

So what to do and what to buy? You need to buy what the motor manufacturer advises. If the “manual” indicates that oil complying with the TC-W3 standard should be added and there are no other comments, then any mineral oil that meets this standard and is credible can be used.

Almost all modern two-stroke engines without the “Automix” system can successfully, without much harm, operate on modern mineral oil, which has a low cost. In motors with the “Avtomiks” system or others, but supplying oil to the crank chamber by means of a special device, mineral oils can also be used, but only those intended for automatic feeding systems, of course, if the manual does not indicate that special oil should be used.

The manufacturer of modern injection two-stroke engines and two-stroke engines of high power indicates the inadmissibility of the use of oils, in addition to those indicated in the instruction manual, this should be strictly adhered to. They need a fully synthetic oil, because the motors were made based on it.

“Synthetics”, which, as already mentioned, has a greater fluidity than mineral water, which is important for the “point” oil supply system, as well as improved lubricating properties, creates a “stable” film on the motor elements that prevents dry friction even in critical cases. The higher the engine load, the greater the likelihood of critical moments, in our case, oil starvation.

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It is believed that “synthetics” does not work well in motors with plain bearings. However, although no special studies on this topic have been conducted (or there is no available information about them), practical experience with synthetic oil suggests that it is friends with plain bearings no worse than mineral water, mainly due to its penetrating properties and the ability to create a tear-resistant film.

So, after all, is it possible to use synthetic oil in “simple two-stroke”? In principle, yes, the motor will not get worse, and sometimes, especially at the time of start-up and at maximum speed, it may even be better. There will also be less deposits in the combustion chamber. At the same time, good mineral oil, which has a low retail price, will allow the clock set by the manufacturer to go away on the motor, i.e., a resource. Therefore, here everyone must decide for himself.

What is the result? Read the instructions and, if the manufacturer recommends using mineral oil, then the use of synthetic is not forbidden, however, due to its high cost, it is not “encouraged”. If the use of a specific synthetic oil is recommended, then mineral oil can no longer be used, even the corresponding TC-W3. in many respects it will not fit the lubrication system of a specific motor.

And the last: on long trips on motor boats, it makes sense to take a jar of synthetic oil with you, which can be mixed with all types of oils for two-stroke engines. It is convenient and can help in difficult times, if not for you, then for others who are in a difficult situation.

KiA No. 4 (214) 2008

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