10w40 vs 20w50


Vehicle engines are not designed to work on oil of one type and one type only. Manufacturers mix and match different oils for different engine types, temperature ranges, gasoline octanes, etc. There is no one-size-fits-all formula that will work in all situations for all vehicles.

The automobile industry has a classification system that is used to classify the performance levels of engine oil.

In this article, I am going to compare one of the two most popular oil types, the 10w40 and 20w50 so that you get clarity on which type of oil to use.

10w40 vs 20w50 oil

10w40 stands for 10 weight, 40th viscosity grade.

20w50 stands for 20 weight, 50th viscosity grade.

The terms ‘weight’ and ‘viscosity grade’ are most of the time used interchangeably and taken to mean the same thing. The actual scientific definition of these is that the term ‘weight’ refers to the SAE (Society of Automotive Engineers) Viscosity Grading scale which is marked in numbers that range from 0 to 60 where 0 marks the thinnest oil (lowest viscosity) and 60 marks the thickest oil (highest viscosity).

A 10w40 oil has 40 units between the two-scale numbers, and a 20w50 has 50 units between the two-scale numbers.

As for the viscosity grade, this is a measure of how much thinner or thicker the oil is than ‘zero’. If you see that oil is of a ‘20’ viscosity grade (i.e. 20w50) it means that at 100 degrees C it will be half as thick as what it will be at 0 degrees C.

This is very important because engine oil behaves differently in cold temperatures than it does at high temperatures. The oil will thicken up at low temperatures and therefore it cannot lubricate as well.

Automotive engines are designed to run on oils that are in between two extremes, thinner oils, and thicker oils. The 20th viscosity grade (i.e. 20w50) is specifically designed for high-temperature situations, while the 40th viscosity grade (i.e. 10w40) is specifically designed for cold temperature situations.

Which is better 10W40 or 20W50?

In short, the answer is that it depends on the situation.

Engines that are designed for lower temperatures and/or cold starts (like those in your winter vehicle) will perform best when using 10w40, I highly recommend Valvoline High Mileage with MaxLife Technology SAE(Check current price on Amazon) while engines designed for higher temperatures and/or used in warm weather (like those in your summer vehicle) will perform better with 20w50, I recommend Valvoline Advanced Full Synthetic 20W-50 (Check current price on Amazon)

Just remember to stick to the viscosity grade that is prescribed by the vehicle manufacturer – do not make a wild guess about what viscosity grade you should use.

Keep in mind that most cars today are built to run on 10w40 oil exclusively throughout their entire lives. If you have a newer car, it is recommended that you stick to 10w40.

For engines that are designed for higher temperatures and/or used in warm weather (like in your summer vehicle) doing an oil change with 20w50 at the end of summer will help prevent the formation of sludge in the engine.

It should be noted that if you do a proper oil change on any car in summer with 10W40 or 20W50 there should not be problems with sludging as long as you change the oil regularly.

This also applies to winter vehicles – as long as you change the motor oil at regular intervals, it is not necessary to use a thicker and more expensive 10w40 oil.

Can I use 10W 40 instead of 20W50?

From what has been discussed above, it is clear that the oil you should use depends on the vehicle, what season it is, how fast you drive the vehicle, and other factors. Using 10W40 in a car that requires 20W50 can cause damage to the engine if done for an extended period of time. The same applies to using 20W50 in a car that requires 10w40.

Some mechanics will recommend using 10w40 or 20w50 as part of their recommended yearly/monthly service schedules regardless of what type of vehicle you drive. If your mechanic recommends this, follow their recommendations as they have more experience than most people when it comes to vehicles and engine problems.

What is 20W 50 oil used for?

20W50 is used when the manufacturer specifies it.

It is also used for vehicles that are designed for higher temperatures and/or used in warm weather (like a summer car) during the winter season.

There are also some recommendations from the manufacturers to use 20W50 in cars that are designed for low temperatures and/or cold starts.

Driving your car at high speeds for extended periods of time may also wear down the engine faster than normal, thus making it cheaper to maintain the vehicle by using 20W50 than 10W40 which prevents frequent changing of the oil. However, this depends on what your car requires and how you drive it. If you drive slowly and have short trips to work, 10W40 will do just as well.

What is 10w 40 oil used for?

10w40 is usually recommended for newer vehicles and/or driven in warmer weather. It should be noted that if your vehicle was manufactured after 2012 there may not be a requirement to use 10w40 unless you drive your vehicle fast or in cold temperatures.

Is 20W50 good for high mileage?

20W50 is not necessarily better than 10W40 for high mileage. If you are asking about needing a thicker oil for high mileage, the answer is no.

If you have a car that has already accumulated 200,000 miles and are thinking of changing the oil to 20W50, it will not improve your gas mileage or the performance of the engine in any way but it will do a good job of keeping your engine running smoothly and be less prone to sludge.

The issue with high mileage vehicles is actually due to driving style and maintenance.

Is 10w40 good for high mileage?

10W40 is not better than 20W50 for high mileage. The difference between 10w40 and 20w50 is simply that the latter is thicker.

As far as gas mileage goes, no oil will improve your gas mileage by changing from 10W40 to 20W50 or vice versa. The way to improve your gas mileage is to drive more efficiently and purchase a vehicle that gets better gas mileage.

Conclusion on 10w40 vs 20w50 Comparison

Each oil has its own qualities and differences, it is crucial to use the correct oil for your car engine to help it run smoother and prevent and engine failures.

Leave a Comment