A synthetic oil is an oil manufactured for enhanced lubrication performance.

The majority of oil lubricants are mineral oils, mixtures of refined fractions of crude oil.

Synthetic oils are fabricated by polymerizing short chain hydrocarbon molecules into longer single chain hydrocarbons. Their lubrication characteristics can be adjusted by controlling the spectrum molecular weights that go into the finished formulation, which usually also includes thickeners.

Advantages

Manufacturers claim the following benefits for synthetic oils

• Better low temperature viscosities. Mineral oils tend to include wax impurities which coagulate at lower temperatures. A typical 10W-30 oils remains liquid at -50C
• Better high temperature performance. Synthetic oils have few low molecular weight hydrocarbons which evaporate at high temperatures.
• Higher purity.
• Decreased oil consumption
• Reduced friction and engine wear
• Improved fuel consumption, through better engine lubrication
• Longer intervals between oil changes
• Resistance to oil sludge problems

Disadvantages

The primary disadvantage of synthetic oils is that they cost significantly more than mineral oils. The manufactures of mineral oils argue that this is offset by a long performance life. As synthetic oils tend to be more fluid they are also more prone to leak through worn seals.

The advantages of synthetic oils are only likely to be relevant in high performance applications such as motor racing and aviation, road haulage, or for general lubrication in extreme environments.

Semi-Synthetic oil

A semi-synthetic oil is a blend of mineral oil with a small percentage of synthetic oil. They are designed to give many of the benefits of synthetic oil without increasing the cost too much.

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