Will Thinner Oils Damage Your Engine?

Can thin motor oils protect your engine?

What do oil weights mean? What does 5W-30 mean? Do thinner oils get better fuel economy? Do thin oils like 0W-20 protect your engine? I spent some time discussing these questions with Mobil 1 engineers and am excited to share what I learned. There’s an incredible amount of testing and verification that goes into labeling a motor oil’s viscosity rating, which is the single most important factor for how a motor oil will perform in an engine. Motor oil is responsible for protecting your engine, removing contaminants, reducing friction and cooling your engine. Plus, motor oil creates a protective barrier between moving metal parts allowing for your engine’s longevity. In this video we’ll use a 6.2L V8 engine cutaway from the C8 Corvette to better see and understand how oil interacts with automotive engines. #Mobil1Partner

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[EngineeringExplained]

*Clarification!* There still seems to be confusion about the viscosity decreasing with heat, yet the number is higher, for example 5W-30.
1. This is explained from about 1:05 to 3:05.
2. All motor oils (basically) will decrease in viscosity as they heat up (become thinner).
3. Motor oils will increase (become thicker) in viscosity as they cool (as demonstrated in the video with graduated cylinders).
4. A 0W oil has a lower viscosity than a 10W oil when it is cold (the number is lower).
5. A 40 grade oil is thicker than a 30 grade oil when it is hot.
6. A 10W-30 (as shown at 2:28) will be thicker at cold temperatures, but thinner at high temperatures, versus a 0W-40.
7. The rating is temperature dependent! There is a cold rating, and a hot rating, which comes from tests (shown at 3:17).
8. Even though the number increases as it gets hot (like 5W-30), the viscosity decreases. It means the oil behaves like a 5 grade oil when cold, but a 30 grade oil when hot. How?
9. Viscosity modifiers are molecules that expand as they heat up, which decreases how much thinner the oil gets as it heats up. It still gets thinner, but not as thin as it could get if the viscosity modifiers were not in there. This is what makes it a multi-grade oil. Because it behaves like different oil grades depending on temperature.
10. In summary, a 5W-30 will decrease in viscosity as it is heated, however its hot rating is a thicker grade oil than its cold rating. See plots in video (2:28) to see what this looks like.

[John-mdld]

As a Chemist, I can confirm that honey does have a higher viscosity than water.

[deane]

As with any car manufacturer there is always one exception to the owner's manual. The current Subaru engines all use the 0w20 oils. The same engine built in Japan all use the 5w30 oils. There are a great many cases of oil consumption in these engines in the US using the 0w20 oils. Most when moving to the 5w30 oils can eliminate the oil consumption issues. Since I live in an area that can have colder winters I elected to run 0w30 oils in my Subarus.

[mik]

I had my subaru tuned by the leading engineer of mitsubishi's efi setup, when mitsubishi closed down here in adelaide/south australia, he started his own tuning business - steve knight racetech. He told me to go higher on the second number to 50 or even 60 (so 10w50) when I do track days or go drag racing, as the oil takes longer to be displaced in the bearings and will prevent spun bearings, and never go to a smaller number unless I wanted to spin a bearing. He built and rebuilt many race engines in his life. I follow that rule, and have never damaged an engine.

[dexterking]

I was always told by a good family member who was a mechanic it’s thinner oil in the winter so the engine warms up faster and a heavy oil in the summer because the engine gains more heat and so far I’ve been doing it past 35 years I don’t have a problem

[foesfly]

I’m glad to see you are gaining industry respect. I don’t think GM shares their very expensive demonstrator models and research data with just Any YouTuber. You have earned this kind of recognition and I anticipate it’s going to continue.

[turbinepower]

I'm an aircraft mechanic and I used to work in gas turbine engines.(jet engines) The synthetic oil used in those engines that reach 60 000 rpm was so thin you couldn't tell the difference between the oil and the jet fuel.

[LuisXGP]

Saying "use what your manual recomends" is just like taking a back seat. Of course for warranty issues and other things, using the spec in the manual is usually what will avoid problems.

But it is not a coincidence, that thicker oils have been used for high milleage motors (like 20w-50 for over 150k km) and that is the part we need to be explained.

[TPEvans]

Tell us about the EPA's role if "encouraging" the use of lower viscosity oils. Years of observation of the EPA informs me their emphasis is solely on fuel economy with zero emphasis on reliability or longevity.

[sptrader]

I just hope that going with lower viscosity oil to increase efficiency by 1%, is not causing 10% shorter engine life. I'd like to see data that proves that engine life isn't sacrificed at all.

[SkaBob]

You can usually drop the cold number with no issues. Cars from 20-30+ years ago may call for 5-30 or 10-30 because there was no 0-30 available at that time and the dealers dealers would have to stock a new oil. I run 0-30 in older cars and trucks at our landscaping company and in my personal cars we had no oil related failures. A 0 weight oil may even provide better protection since it can quickly get into all areas of a cold motor.

[Uracantaino]

Mazda recommends 0W-20 for my engine. For the same engine, in Italy Mazda recommends 5W-30. Why? I suspect 5W-30 is a better oil for this engine and there are no CAFE requirements in Europe.

[Chris_Troxler]

"Always use what's recommended in your owner's manual."

Me, channeling my inner Derek while buying a gallon of Rotella 15w-40 and a bottle of Lucas for my F-350: "It's got dinosaurs and vitamins in it. Plus, it was on sale."

[donfinkey]

Wow, I’m a 67 year old guy who just learned some thing new! My 19 Camry uses 0 W 16 and I was wondering how could this oil protect my motor. Thank you.👍🏻

[henrikrolfsen]

Climate plays a major role in oil selection. If you live in Chicago, extremely cold starts are normal in winter. A lower "W" number can save your engine, and allow for faster warm up. But, if you live in Los Angeles, winter freezing are not an issue. During sustained driving on long freeways, and highways, and especially long trips through desert conditions, means your high end viscosity can become critical. It is always smart to allow warm ups before driving after long cold nights. Change your oil before it begins to break down. This keeps internal dirt, tar, and debris to a minimum. Always use better brand filters!

[georgecolbert]

Good video. Other things to consider: Over time engines have been designed with tighter bearing clearances, thus the thinner oil is needed. On the other hand, ring seal will suffer if the oil is too thin resulting in loss of power. under load.

[theslimeylimey]

When the automotive industry talks about 'adequate protection' for the 'life' of the engine what they really mean is that it won't fall apart or start smoking during a cars typical life span. That does not automatically mean a different oil won't offer more protection or extend the life of the engine. I'm skeptical of claims the automotive industry make. Automatic transmissions that are 'superior' to manuals for example where they are horribly programmed and refuse to dowshift yet upshift at every opportunity because drivability was tossed out the window in favor of fuel economy.

[punjabob]

He's right, nobody with a Corvette cares about fuel efficiency.

[dustin]

Thanks for the video. The EPA is ruining the ICE. For example, take my 2.0T Honda Accord. 0W-20 is the spec for North American vehicles. However, other parts of the world call for 5W-30. Additionally, fuel dilution is a major issue with Direct Injection engines, like mine. The thinner the oil, the more damage fuel do to the oil. These long intervals are a nightmare for long term internal damage to a motor because of that. I'll be running 5W-30 on 5, 000 mile OCIs from now on, on all of my Honda engines.

[SmilesPerGallon-]

“Always always always” as I drive back from Oreillys with 0w-40 for the winter. Great video