Heavy oil is different from general oil, mostly its viscosity is too thick to be exploited with normal methods.

稠油不同于常规原油，主要是粘度大，难于用常规方法开采。

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These oils will always have the correct thickness when hot and will still be too thick at startup as with all oils of all types, regardless of the API / SAE viscosity rating.

这些油在策动机正常温度的时候总是保持着合法的厚（粘）度，在启动时也会像所有油一样变的过于粘稠，无论 API/SAE 什么粘度级别都如许。

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