Can you use either 5w20 or 5w30 in your car’s engine? Are they interchangeable? Will changing oil grades cause engine damage or even void your warranty?
We have consulted the Society of Automotive Engineers (SAE) to answer this question. Yes that SAE, the industry association responsible for creating a worldwide grading standard for oil manufacturers to adhere to when grading oil around the world. Using data collected by the SAE we will answer these questions to get a current answer from industry experts.
By Maurice Rodriguez
November 1, 2021
Table of Contents
Can you use 5w30 instead of 5w20?
Yes. Using a higher viscosity oil such as 5w30 will not harm your engine temporarily. However, car manufacturers work closely with industry oil experts like the SAE to establish consistent standards for producing accurate fuel efficiency and operating conditions for your engine. These standards allow car manufacturers to meet MPG and engine life goals using specific oil grades and viscosities. In fact, according to the SAE, “low viscosity engine oil usage to improve fuel economy not only decrease the frictional loss of the engine oil seal but also have no defect in the performance.”
Even though you can use 5w30 instead of 5w20 with only marginal operational differences in fuel economy and engine wear if the manufacturer recommends using a specific oil grade this could void your powertrain warranty. But, if you are warranty has expired you can use either oil without any issues.
While no short-term damage will occur to your engine by using a more viscous oil like 5w30. It is recommended you follow manufacturer guidelines whenever possible.
How Motor Oils Work In A Gas Engine?
Motor oil in a combustion engine is used to lubricate the engine parts to decrease friction as they move past one another and to dissipate the heat that is created from friction.
The video shows you how the motor oil starts in the oil pan, gets pumped by the oil pump driven by your engine, goes into the oil filter, and then pushed into oil galleries that lubricate the piston, crankshaft, cams, and then return to the oil pan.
Understanding Motor Oil Grades
The Society of Automotive Engineers (SAE) is the organization that is responsible for creating the SAE J300 standard for defining engine oil viscosity properties for monograde and multi-grade oils.
The SAE J300 defines an oil’s low-temperature viscosity properties and high-temperature high shear temperature viscosity. When you are reading the grades on a multi-grade oil the first grade (5w) will indicate an oil is rated for winter temperatures. The second grade (30w) indicates the oil operating temperature once the full engine temp is reached.
A monograde engine oil like you would use in a lawnmower only meets the viscosity grades needed for specific temperatures. A 30w oil is a winter oil best suited for cold climates where temperatures go below -32°F. A SAE30 grade engine oil is best suited for higher temperature climates where cold climates are not a concern.
What does low viscosity in engine oil mean?
Low viscosity refers to the ability of a liquid to resist breaking down. In engine oil, it refers to the oil’s ‘thickness’. 5w-20 motor oil will be less viscous than 5w-30 and will be thicker. A more viscous oil will offer higher operating temperature protection and better protection in hotter climates.
5W20 Vs 5W30 Oil: What’s The Difference?
To understand the main differences between these two oils you have to understand the four main criteria by which engine motor oils are graded and classified.
High-Temperature High Shear Viscosity
According to the SAE, HTHS is the most important factor in the viscosity of engine oil. This is because “HTHS viscosity is a better predictor of bearing wear performance than oil film thickness.” These test results were taken from a 45 taxicab field test in New York City. They found that higher viscosity engine oil performed better in high wear operation. But does that mean you should switch to a higher viscosity engine oil? The engine manufacturer’s engine oil recommendation is usually the best oil to use as they do testing-based fuel economy, engine wear, and optimal operating temperatures. Switching to a different oil grade may result in sub-optimal engine performance and frictional wear on internal parts.
Low Temp Cold Cranking Viscosity
Low-temperature cold cranking viscosity is a simulated test of the oil viscosity in a crankshaft in cold climate start-up situations. It measures the lowest temperature a motor oil can protect engine parts. As you can see in the chart below the first set of numbers in a motor oil grade are indicators regarding at which temperature the motor oil can perform
| Grade | Maximum Cold Cranking Temperature |
| 0W | -31°F |
| 5W | -22°F |
| 10W | -13°F |
| 15W | -4°F |
| 20W | 5°F |
| 25W | 14°F |
Kinematic Viscosity
This is the most important measurement and the second part of an engine oil grade that measures a fluid’s resistance to flow at a specific temperature due to gravity. This measures the force required to move the engine oil through an orifice like in the oil lines in your engine.
The higher the viscosity an engine oil is rated the higher the kinematic viscosity force required to push the engine to the vital parts in your engine.
Climate Types
The main differences between 5w-20 and 5w-30 are the ability for 5w-30 to handle higher operating temperatures of hotter climates. It is capable of handling higher temperatures because of its higher viscosity grade before it begins to break down.
5w-20 vs 5w-30 Chart
Can You Mix 5W-20 And 5W-30 Oils?
If you are in a situation where you don’t have the recommended engine oil and ONLY have access to one oil type and your engine needs an oil, you can mix engine oils with any issues. It will not harm your engine or engine parts in any way. But, you should use the recommended engine oil at your next oil change.
What Is SAE Oil?
SAE Oil (Monograde or Straight Oil) refers to an engine oil with a single number grade like SAE30 or SAE30w. SAE30 is designed for hot climate operation whereas SAE30W is formulated for cold climates. Unlike, multi-grade oils (like 5w-30) that are suited for both cold and hot climate operation.
Detergent Vs. Non-Detergent Motor Oil
Most engine oils today have been formulated with detergents, anti-oxidants, corrosion inhibitors, viscosity index improvers, and anti-wear agents. The detergents help keep clean your engine parts to prevent ash deposits from accumulating when oil is burned. Detergent motor oils are the most commonly used motor oil since the 1950s because of their protective benefits.
Non-detergent motor oils are essentially mineral oil without any additives that help keep your engine clean from deposits, or any other protective additives. It has no advantages over motor oils with detergents and is recommended only for older non-critical gasoline engines that operate under mild conditions like a lawnmower or farm tractor.
You would be hard-pressed to find any dealership, oil changing shop, or mechanic shop that would carry a non-detergent motor oil.
Synthetic Vs. Synthetic Blend Motor Oil Vs. Conventional Oil
Synthetic oil is a refined oil-based lubricant that has been refined to have superior qualities over conventional motor oil. Some of the key benefits to synthetic oil are a more chemically stable product, doesn’t oxidize as quickly, or breakdown as quickly.
Synthetic oils are engineered to combat deposits by incorporating detergents, reducing wear by using anti-wear agents, providing high-temperature protection using viscosity index improvers by preventing the oil from thinning as temperatures increase.
Since there is no industry definition for synthetic blended motor oil its benefits and shortcomings are difficult to quantify and in our opinion should be avoided. If you are going to go synthetic, then go full synthetic. Why would you use a middle-of-the-road product that costs more and make vague promises about its performance?
In comparison, conventional oil seems to be an antiquated solution for modern engines but will still protect your car’s engine in a pinch. But, seeing how most synthetic oils are equally priced and offer superior protection to modern engines and older engines as well there is no reason why you shouldn’t give synthetic oils a try.
What Happens If You Put A Conventional Oil In A Vehicle That Requires Synthetic?
Potential engine damage to the oil seals, oil pump, pistons, crankshaft, and cams. You can always use any oil you want but not using the manufactures recommended oil could cause serious irreparable damage to your engine. Most modern engines use light viscosity engine oils like 0w20 because they allow less stress, higher compression, and extended protection on the engine components than conventional can provide. If your manufacturer requires a specific viscosity like 0w20 it is because it has specifically engineered your engine’s fuel economy, frictional stresses, and operating temperatures based on the performance of your oils specific properties. If you use conventional oil that cannot meet the grade viscosity, then you could potentially cause serious issues to your engine parts.
Which Motor Oil Should I Use?
After all, we have read this should be an easy question to answer. The best motor oil you should use is the one your engine manufacturer recommends. Synthetic oils seem to be the future of the automotive industry and are definitely here to stay as they have many benefits over conventional oil. Synthetic oils keep your engine cleaner, are more versatile at lower and higher temperature climates, have anti-wear agents, last much longer, and provide better lubrication.
But, if cost is a factor and your engine manufacturer doesn’t specifically require you to use a synthetic oil like 0w20 then I don’t see any harm in using a conventional oil as long as you change it at the specified intervals.
Best 5W-20 Oil
Castrol GTX MAGNATEC 5W-20 Full Synthetic
Castrol GTX with Magnatec is a specially formulated full synthetic engine oil that according to Castrol has intelligent molecules that adhere to critical engine parts to provide an extra layer of protection during startup. Castrol claims this oil offers six times better wear protection than required by industry standards.
Pros:
- Fully synthetic
- Six times better lubrication than the industry standard
- MAGNATEC protects the engine during startup
- Inexpensive
Cons:
- None we could find
Best 5W-30 Oil
Valvoline Advanced Full Synthetic SAE 5W-30 Motor Oil
Valvoline’s Advanced Full Synthetic SAE 5w-30 motor oil is the most popular bestselling motor oil. It offers full synthetic benefits of having anti-wear agents that provide 40% more wear protection than other oils. Its detergents give you 25% more protection from oil ash deposits when the oil burns when it breaks down.
Pros:
- Anti-wear additives help protect engine parts
- Full synthetic formula offers better protection against heat
- Extra detergents help keep the engine clean
- Anti-oxidants resist oil breakdown
Cons:
- None we could find
Best 0W-20 Synthetic Oil
Mobil 1 Synthetic Motor Oil 0W-20 Advanced Fuel Economy
Mobil 1 Synthetic 0W-20 motor oil is a full synthetic oil that gives you protection up to 10,000 miles between oil changes. It also claims enhanced fuel economy benefits as it reduces frictional losses due to piston engine wear. Mobil 1 0W-20 full synthetic engine oil will offer your engine low-temperature protection up to -40°F which is essential during cold weather starts.
Pros:
- Protection up to 10,000 miles between oil changes
- Enhanced fuel economy
- Cold weather protection all the way down to -40°F
- Extend Engine Life
- Cleans engine deposits
Cons:
- None we could find
Conclusion
Choosing the right engine oil is a somewhat complicated decision when there are so many claims and terms to try and understand. But with a few minutes of research, you can make an educated decision that we help you keep your engine running right. Full synthetics offer a wide range of options that can offer low-temperature protection, reduced engine wear, superior heat protection, and even help extend the life of high mileage engines.
We hope we have answered all your engine oil question so you can make an informed decision.
We are all things cars.
Maurice is an avid car enthusiast, foodie, and loves hard rock. When he isn’t writing blogs he enjoys traveling and sight seeing.