10W 40 and 20W 40 are types of engine oil. To keep an engine running, engine oil is important.
The functions of an engine oil is to lubricate the engine, protect the engine from high temperatures and let the engine start easily at low temperatures.
Our discussion on which oil to choose will depend on these very basic qualities itself. So, let’s dive in.
Both of these have samer rating which is 40. Here, rating means viscosity. Both of these oils will have a rating of 40 at 100c. Similarly, a 10w 30 will have a rating of 30 at 100c. The lower the number the less viscous it will be i.e., the thinner it will be.
A 10W 40 will have a viscosity of grade 10 when cold and likewise, a 20W 40 oil will have a viscosity of 20 when cold. But both will have the same viscosity of 40 when hot.
Generally thicker oils are used in heavy duty vehicles which have turbocharged or supercharged engines. These engines tend to run hotter than normal engines, so they need thicker oil which can absorb heat better and dissipate it. Viscous oils perform better when hot and so the engine can run without any hindrance.
Modern day engines tend to run hotter than old traditional engines as modern engines generate more power with smaller engines. For instance, we can consider the example of a new inline 4 cylinder engine and a 5.0 Triton V8 from the 2000s. The former is a new generation engine which produces 250hp power despite being smaller than the flagship level engine of the 2000s Triton V8.
Also, new emission norms force engines to be controlled in a way which may lead to more heat generation. Hence, the rating of 40 is justified.
Now, let us judge which will be a better choice: the 10W 40 or the 20W 40.
To understand the differences, let us first see what the alphabet “W” denotes in the name of the engine oil. Here, W means winter. It means the maximum viscosity at lower temperatures. The lower the number before W, the better performance in cold temperatures.
Motor oils have a aWx grade. A 10W oil has a lower aWx rating and a 20W has a higher aWx rating. Once the engine gets sufficient heat then these oils will attain x grade viscosity.
10 or 20 before W tells us that the viscosity will be that when cold and 40 when they are hot.
This in turn, will affect the cold start performance of the vehicle. Your vehicle will take more time to start if the oil has a higher W rating. This will stress out the starter motor more and will deplete the battery and also since the oil will remain thick, so it will not flow easily to all the engine parts and your engine parts may wear out faster. That’s why lower W rated oil is recommended for countries with extreme cold weathers.
A 10W oil can provide better lubrication and performance over a wide range of temperatures than the 20W. Additionally, for high mileage vehicles, a 10W will be suitable
20W 40 is slowly withering off the market as they are not ready for all weather performance. Everyone will want an all weather performance oil, isn’t it? Nowadays, most cars come factory shipped with 5W oils as they are very efficient and strike a perfect balance for hot weather and cold weather. It also gives car owners the assurance to venture out in different places without getting caught off-guard.
Since, car manufacturers do not recommend 20W anymore, so slowly less and less cars are using it.
If your car came loaded with 5W oil but you start using 20W later then you will not notice any problems right away. But slowly, after 6 months or 1year, your engine will show signs of wear out and may burn your pockets during repair.
Various engine parts can be damaged due to the higher pressure of the engine oil because of it’s higher viscosity. Piston rings may get damaged and the engine may start producing blue smoke. Along with this, as we have discussed, the problem of starting in cold temperatures will be huge.
Meta desc- 10w 40 or 20w 40 for your car? Choose the right one today and save your engine. Help your engine survive longer by reading this blog!