Multigrade vs. single grade oil: Which is better for your engine?

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In the fall, farmers think of harvest, young boys think of football, and pilots’ minds turn to whether to use single grade or multi-grade oil in their airplanes for the winter. 

So which one is better for your engine?

Aeroshell Oil W 15w-50

If we look at the benefits of a multigrade oil, most of the pluses are in cool or cold weather.

Multigrade oils flow better during a cold start, so the engine cranks faster, which is easier on the battery and starter. Another plus: Multigrade oil gives you a better chance of starting, especially if pre-heat is not available. 

The really big benefit is that multigrade oils get to critical bearing surfaces quicker after the engine does start. 

So, what could be the down side of a multigrade oil? 

Multigrade oils leak more than single grades. This means that if your aircraft tends to mark its territory, a multigrade oil will increase the markings, which can be a problem on your floor and give your mechanic a headache.

Oil on the hangar floor is not a welcome sight. (Photo by William E Dubois)

Also, if your intake guides are too loose, your engine will use more oil with a multigrade oil.

The gray area in this discussion is oil consumption past the oil rings.  Multigrade oils tend to reduce the oil consumption past the rings by 30% to 50%.

Most pilots think that the lower the oil consumption the better, but that is not completely true. If you remember my

This post was originally published by General Aviation News on . Please visit the original post to read the complete article.

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