5w20 vs 10w30 – Which Of Them Is The Best Of Your Car?

As opposed to other engine oil comparisons, this pair have less in common as they don’t share any similar figures. The numbers in the names stand for their viscosity rating under different conditions.

The letter “W” in each of the product name stands for the cold viscosity and the number before it represents the cold viscosity rating which increases as the number does in various products.

The number that comes after “W” stands for the hot viscosity rating which represents its resistance against getting thin and ineffective due to the influence of heat from the car’s engine.

So, how different are these products? And which is the better of the duo?

The variation in the numbers of the product name clearly indicates that the major difference between the engine oil product types are their viscosity. This is also divided into two categories since engine oil malfunctions both in extremely cold and extremely hot temperatures.

The variations are put in place to cover these extreme conditions and keep your car functional. It’s however up to you to make an informed decision on what your vehicle needs based on the strength and weakness of the particular type you choose.



5W20 :

This engine oil type has a cold viscosity rating of 5 at zero degrees Celsius which works fine at cold regions. This means that when the temperature gets cold around the engine oil, it doesn’t get so thick that it can’t lubricate the engines or manage the fuel consumption and fuel efficiency in your vehicle.

It’s hot viscosity on the other hand has a rating of 20 which is pretty good under normal temperature. However, when the temperature gets a hotter than usual, the oil gets so thin that it positively influences your gas mileage but at a greater cost. It becomes so thin that it can’t properly lubricate the engine.

Given its temperature range, it has very limited capabilities especially in extremely hot conditions. It is a good choice in cold climate areas such as Canada, the Northeastern parts of the United States or other areas with ambient temperatures as low as -30 degrees Celsius on a cold day and about 25 degrees Celsius – normal vehicle temperature on a sunny day.


10W30 :

With a cold viscosity rating of 10 at zero degrees Celsius, this engine oil type has better lubrication at lower temperatures. This thickness works best for old engines that are already falling apart given the sealing capabilities that it also possesses. Therefore, the engine won’t need to do that much work to get the engine started or to get the parts lubricated even when the temperature is freezing cold.

It’s hot viscosity rating is just perfect, sharing this particular feature with the popular 5w30, and only being different in the cold parameter. This hot viscosity rating is right in the middle and works perfectly well for any engine type – old or new – in harsh weather conditions.

However, compared to 5W30, this engine oil has a smaller temperature window giving its best at temperatures above -18 degrees Celsius and heated temperatures below 30 degrees Celsius.


How do both of these products affect your gas mileage?

The thing about engine oils positively influencing the gas mileage of vehicles is that it affects the oil’s ability to lubricate the engine. Technically, the thinner the oil, the better influence it will have on fuel efficiency. With that in mind, it is pretty clear that during at hot temperatures, the 5W20 better serves the gas mileage of your vehicle.

The 10W30 on the other hand is more pertinent to keeping every working part on point and their operations balanced by moderating lubricating the engine in extremely cold weather and retaining its quality viscosity in extremely hot conditions.


The interesting thing about this comparison is that both products have one good side to them, and choosing based on which downside you can tolerate would be dependent on your personal requirements.

For example, the 5W20 is better suited to cold regions where the viscosity required of the oil must be enough to get the engine moving during very cold periods while the 10w30 is better suited to hot conditions where heat doesn’t have a significant effect on the viscosity.

Conclusively, for old engines, use the oil with the thicker texture for better lubrication and blockage against leakages. For hot areas such as Texas of California, make sure that your engine oil has a minimum viscosity rating of 30.

We suggest you read our guide on the best synthetic oils to help you find high quality oil for your vehicle.

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