Gear / Parts Choosing Motorcycle Engine Oil: An Expert Weighs In

Choosing Motorcycle Engine Oil: An Expert Weighs In

If you’re a fan of Moto2, you are familiar with the Liqui Moly name. It adorns the fairing of the Liqui Moly Intact GP motorcycles raced by Tom Lüthi and Marcel Schrötter. A best-selling petrochemical manufacturer in Germany, Liqui Moly is led by outspoken CEO Ernst Prost. Although not a big name in the United States, Liqui Moly is sold in 150 countries with over a half-billion dollars in annual sales, and has been in business since 1957.

Choosing Motorcycle Engine Oil - Moto2

Choosing motorcycle engine oil—mineral, semi-synthetic, or fully synthetic—bedevils motorcyclists around the globe. Oliver Kuhn, deputy head of the oil laboratory at Liqui Moly, has provided us with his insight into this highly technical matter in this Q&A session.

Q: What kind of oils are there?

Oliver Kuhn: Motor oils can be roughly divided into two categories—mineral-based and synthetic oils. Mineral oils are becoming less and less important for motorcycles because they do not offer such high performance. Modern engines demand much more from the oil than old engines. Only synthetic oils can meet these requirements.

Q: So, synthetic oils are the better oils?

OK: Yes, but you can also mix a mineral oil with a synthetic oil. However, such semi-synthetic oils are playing an increasingly smaller role in the market because their performance is not high enough due to their mineral content.

Q: Are all synthetic oils are similar?

OK: Unfortunately, no. There are two different ways in which synthetic oils can be produced. By one of these methods, a so-called PAO (poly-alpha-olefin) oil is obtained at the end. This is the classic synthetic oil as it came on the market in the 1970s. It is chemically very pure and, therefore, very effective—but also very expensive to produce. With the other approach, the oil is produced by hydrocracking, which is why these oils are also called HC oils in technical jargon. HC oils are more modern and came up in the 1990s. Today, they offer the best possible performance for all modern engines.

Q: Should one use a PAO oil or an HC oil?

OK: This choice is often not even available. Almost all oil development nowadays takes place on the basis of HC oils. Many oil specifications can only be met with HC oils.

Q: How can I tell what kind of synthetic oil it is?

OK: That is not so easy, because there are no uniform terms here. In the USA, for example, both PAO oils and HC oils can be described as fully synthetic, but in Germany, only PAO oils may be called synthetic. That is why we give our HC oils the label, Synthesis Technology. Other oil manufacturers use terms such as 100% Synthetic or Synthetic Mix, where it is not clear what exactly is meant.

Choosing Motorcycle Engine Oil - Oliver Kuhn interview
Oliver Kuhn, deputy head of the Liqui Moly oil laboratory

Q: That can be quite confusing.

OK: True, but the question of which synthetic oil is actually meant in a particular case is of no importance to drivers and workshops. It is not about which oil is supposedly better. The decisive factor is that the oil meets the specifications which the motorcycle manufacturer has set for that model. This is given in the manual of the motorcycle, or you can use our free Oil Guide at the Liqui Moly website.

Q: So, if the specification is right, it doesn’t matter whether it’s a PAO oil or an HC oil?

OK: Correct. In any case, the additive packages are becoming increasingly important. Today, they are the most important component of a motor oil, besides the actual oil. They provide a large part of the motor oil’s performance. With some very modern motor oils, the base oil is hardly more than just the carrier fluid for the additive packages.

Q: So why are there always discussions about which synthetic oil is the better one?

OK: This is an echo from the past. When the first HC oils appeared 30 years ago, the quality difference to PAO oils was even greater, but that was a long time ago. No expert would have such a discussion today.

Editor’s note: In addition to motor oil, Liqui Moly makes transmission oil, coolants, hydraulic fluid, suspension fluid, chain lube, grease, and cleaning supplies for motorcycles.

Don Williams
Don Williams
With 50 years of riding experience, Don Williams is a fan of all kinds of motorcycles. He enjoys sport bikes, cruisers, dirt bikes, touring bikes, adventure bikes, dual sport bikes, and rideable customs. Ask Don what his favorite bike is and he will tell you, "Whatever bike I'm on."

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