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SAE? API? 10W40? 50 weight? We decipher the oils so you know how to choose the best one for your bike


July 30, 2017   


Sergio Otoya 


10W40 ?, 15W40 ?, 10W50 ?, API ?, SAE? ... It is likely that you find yourself drowning in an oily sea of doubts when you pick up a bottle of oil and you start reading the characteristics written on the bottle. This article will educate the average motorcycle rider into knowing what all that jargon means. In fact, it's very easy to understand.


There are several scales that measure the viscosity of the oil, but in the case of engine lubricants, the SAE (Society of Automotive Engineers) grades are used, which relate the viscosity of the oil to the operating temperature of each lubricant. SAE J 300 is responsible for defining the degree of viscosity of each lubricant.


The higher the number, the better the maintenance of viscosity at high temperatures. But in cold oil must be kept very fluid so that it can be distributed well throughout the engine, protect mechanical parts that are in motion and encourage start up. As oil cools down, their viscosity becomes thicker or heavier. 




One for winter and one for summer What madness!





This leads us to have two types of oil: the monograde and the multi-grade. The former maintain their viscosity in limited ambient temperature conditions. For this, the SAE standard establishes a degree of viscosity. Grades that have a W (Winter and not Weight) have a good behavior at low temperatures. The lower the number is the fluidity of the oil at low temperature or at start-up. For example, a 0W will be good when very cold and 25W will be less fluid. From here the grades that do not have this W are those indicated for high ambient temperatures.


This monograde oil generates a very basic problem: in winter, you have to use a "winter" oil (SAE 0W at 25W) and in summer, you have to replace it with another oil that depends on the weather, what is called " summer oil  "(SAE 20 to 60). Imagine the expense that this would mean for your pocket when doing maintenance to your beloved motorcycles.




But, this problem is ended using a multigrade oil or "for the whole year". It has no mystery. This lubricant is based on an SAE W grade oil and viscosity improvers are added later. In this way a good behavior is obtained in cold and, when increasing the temperature, it works like a summer oil. This achieves an oil that can be used all year keeping a viscosity more or less stable regardless of the ambient temperature.

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