*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.

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

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

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.

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

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.

That's the best looking, cut away motor, I've ever seen!

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.

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.

"As long as the engine lasts for the warranty period, we don't care what you put in it." -Ford Executive

"Use what the manufacturer recommends" ...until they recommend a lower viscosity on the same motor later in production to increase fuel efficiency at the expense of wear.

I love you because you said 'criterion' for singular rather than the plural version "criteria." BRAVO!

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.

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.

Use manufacture recommended oil. Mazda RX8 has left the chat.

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

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.

"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."

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 KZfaqr. You have earned this kind of recognition and I anticipate it’s going to continue.

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.

I've seen technicians at dealership using 0w-20 oil for cars that are supposed to use 0w-30 in tropical weather. I looked up the manual and it specifies that 0w-20 is supposed to be used on cold weather and winters and not for summer / tropical weather. So always lookup in the owner's manual. The oil gets thinner when the operating temp gets higher. If you drive your car hard then please select the heaviest weight oil specified in your owner's manual.

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.

That cut-away engine is a work of art. I would have that in my living room as a sculpture (if my wife would let me...).

Excellent video, this what I was looking for, no one really unstood the details and explained it the way it is explained in this video

-0w30_for coldest months_Little Thinner Best protection for cold cranks and wear. -5w30 or 0w40_for all year round is balance. -5w40_for Summer months_little thicker was popular 10years ago and vehicles are reliable Also best for warm places like 10w30. -10w40 is thicker best for tropical or hot places all year round. -Addition: 5w50 and 10w50 is high performance horsepower or racing. Note: oil gets thinner when engine is running due to hot temp, no protection when its too thin and it will have leakage and it will evaporate and lose oil. Your oil viscosity depends on weather and type of use of vehicle. Hauling towing racing high performance torque and hp of use best is 40 or 50 viscosity or even 60 for super cars.

No one: Engineering Explained: makes a video just so he can write off his organic honey on his taxes

As a bear, I can confirm that honey is delicious.

I never realized the bearing drop test bud. That’s awesome 👏🏾

The graph and explanation at 11:00 is fantastic. That is the most helpful thing in the video for me, and it makes complete sense.

Thing with the manufacturer recommended oil weights is that they’re universal for climate regions. They’re meant for the dead of a Canadian winter or August in Texas so you CAN fudge those numbers depending on the climate where you live, just don’t go down (ie 5w30 to 5w20). Up though, especially for the year-round “hot” climates like Texas there is absolutely no problem raising those numbers. In fact it’s probably recommended. You’ll never have the low flow cold start problems to worry about but rush hour traffic on the freeway when it’s 105*F ambient and 130*F+ on the road with your AC cranking and no airflow through the cooling system your engine will appreciate the extra viscosity.

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.👍🏻

I have come across instances where running a higher grade oil in a higher milage or worn engine can be helpful. There is one scenerio in particular that i have experienced better results: A 2013 Ford Taurus 3.5L n/a that had over 120,000km on the engine, the engine showed signs of poor maitenance and increased wear internally (i had the engine covers off). After discussing it with the owner it was found that putting a large sum into the vehicle to rebuild the engine was not worth the value of the vehicle. A lower cost solution, a comprimise, was reached to go up from 5w20 factory oil grade to 5w30, and use a high-milage oil blend. After switching to this oil, fuel economy change was negligable, however the previously noisey engine had now quieted down remarkably. This vehicle now has an additional 60,000km on it and is still running excellent, and quiet. There are many tips and tricks you can utilize to extend the life of your vehicle, you just need to make application specific determinations as per your scenario. If you drive your car like you stole it everyday, high load, high stress conditions, then sometimes changing grades is worth it. Also if you have an older car, with high milage or high wear, changing grades can also be benificial, and if your warrenty is likely expired there is nothing stopping you from consulting good resources and making your own choice as to what grade you use.

I’ve been trying to figure this out for years. Finally I understand, thank you!

Oil lubricates the engine Dodge 5.7 camshafts and lifters left the chat.

Loved the water skiing analogy as it relates to the piston to cylinder wall interface.....very clever !!

Best video in describing viscosity and the relationship with weather and engine temperature.

I actually remember the days of factory carburated vehicles and running a thinner oil in the winter. Good stuff and brings back positive memories.

As a sales person in a parts store, I can tell you it's very frustrating and cringeworthy when someone comes in and wants 20-50 for their everyday driven 4 cylinder Honda/Toyota, etc. This happens often. I always recommend sticking to what's marked on the oil cap.

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!

So clear, easy to understand for an ordinary person who is not well conversant with automobile engineering principles .. thanks dear for a wonderful guide

"You should always, always, always" Me: Haha. Lucas oil treatment goes glug.

Surprised he didn’t mention how some car manufacturers will have a graph in the owners manual telling you what viscosity to use depending on your average or ambient temperature where you live

Dear you have explained so well in a very lucid manner , all doubts solved

Very informative and well done, thanks!

(Oil Guy forums implode) What was that noise?!? Oh, someone said “Viscosity” on the Internet.

I had a big argument last week about this Most people want thick oil But they dont understand that thick oil cant previde lubrication when cold and thin oil can go between those tiny gaps that modern cars have now. Just use the oil the what the manufacture recommand

Best explanation I ever had!! Thank you !!

i used to work in an auto parts store back in the 70s...we had a 3rd option back then which was straight SAE 30.....some vehicles used it but oils got better over the yrs thus protecting more at the lower/start up temps AND the tighter tolerances that occurred as the engines got higher revving and more fuel efficient

Wife's 2016 Odyssey calls for a 0w-20 oil and was consuming a good bit after 120k miles. I swapped to 5w-30 and it runs much better and didn't notice any decrease in MPG.

I use a 0w instead of the recommended 5w on my car, but I live in Canada 🇨🇦. So the 0w is definitely better in -30 celsius.

Outstanding presentation. I have a much better understanding. You are very clear and precise.

Thanks .for that like always you take a very complicated subject and bring it down to a level where we can understand. That was very clear. Thank you.

“ALWAYS use manufacturer specified oil viscosity” Everyone in the comments- “Nah...”

Its funny how most people are so quick to take the advice of a friend who heard from a mechanic that doing _____ will give your car more power/reliability/efficiency. But refuse to believe what is written in the official service manual from the people who designed the thing!

I have a 2003 Ford F250 Super Duty truck with a 5.4 motor gasoline engine. I do not use the recommended oil for my truck. I noticed if I use the recommended oil 5W-30 the motor starts to make a ticking noise. It has 366,000 miles now. I been using regular castrol gtx 20/50 for 5 years now and changing the motor oil every 2500-3000 miles. I haven tried the synthetic 20/50 motor oil and my trucks engine makes a ticking noise with that one too. I am surprised how great it sounds just with the regular 20/50 castrol gtx oil. This truck does not want to give up yet. Amazing truck!

Great explanation thanks

On my current car Audi recommend 5W30, but on a couple of occasions i found it too thin for the summer in the traffic jams to the point where the "low oil pressure" lamp came up so i drove it to the garage and after they disassembled the entire engine found out there was actually nothing wrong with it, it was just the oil wasn't viscous enough at these high temperatures (usually anything above 40°C). And because there wasn't 5W40, went for the 0W40, the problem went away immediately and later in the year i found it helps for much smoother starts in the cold winter mornings and nights. It's strange however that manufacturers don't include table with different climates and recommendation of oil grade. I remember in my 1990 VW Corrado manual the 15W40 was recommended but in temperatures lower than -15°C or altitudes above 1500m the 5W40 was noted as well as when there's a lot of short city driving.

Long story short: as long as the oil is thick enough to provide oil pressure that's high enough to make sure there's no metal to metal contact, it's thick enough. Any thicker is wasted energy at best and accelerated wear at worse since the excessively thick oil can't flow well enough.

Engineering Explained is great for snow storm days. I can’t put this guy away.

Dear Jimbo, I love watching you do ‘stoopid stuff’!

I've found that using thinner oils results in moderate oil consumption. When I use 5W30 my 4 cyl car uses no oil between 5000 miles OCI. Using 5W20 the same engine is about 1/2 qt low by 5000 miles. The engine has 45,000 miles.

Let’s talk about oil filter bypassing as viscosity goes up.

Thank you! This was very educational

Very interesting! I better be careful with using modern oils in some of my older vehicles, although as stated a slightly lower winter or higher summer number isn't as bad as going the opposite way. Thanks for the info.

"Bearings get lubricated" My lawn ornament disagrees.

Just subscribed and I'll tell you why. Instructions were clear and concise without overbearing music to contend with, really no "extras" thrown in just to hear your head rattle, and finally camera work was well done without shaking or wondering. This should be a lesson for other KZfaqrs. Thank You, JD

I had a 1964 mercury with a 351 windsor engine, I used a 10w30 oil with a can of STP It ran really good with regular tune up and oil change every 12,ooo miles

Critical comment: Using the oil that your engine was designed for. In 2013 I was a camp manager for a man camp in the arctic where we had 2 400KW Cat generators. One was new, one had about 2000 hours on it. They ran as a primary and a secondary. The primary would run full speed 24 hours a day until it had 250 hours on it then the secondary would be warmed to operating temp (they both had engine heaters to keep them warm enough to start in sub zero temps) where it was then switched to primary and the other was shut down for service to wait for the running generator to reach 250 hours. Fast forward to the new engine having 750 hours. Some brain surgeon at the Cat dealer decided that "hey this is the dead of winter so we should switch to a 10W-30" instead of the 15W40 Shell Rotella T they were using (after 2 oil changes with 15W-40). After they switched and I found out I told them that that wasn't going to work. That Cat engine had injectors that run on oil pressure to inject the diesel into the engine, the lower viscosity oil was a problem in those engines even or especially at sub zero temps. Well the engine made it to 854 hours where it locked up about 2AM (they always failed in the middle of the night) I had to warm and switch over to the secondary engine to keep the camp warm. The problem was that the secondary engine was also full of the 10W-30. The primary was replaced in a few days with the same model of Cat generator after tearing down part of the shack the generators lived in (shack was to keep the generators from being under 8' of snow all of the time they still ha to be shoveled out sometimes). Meanwhile another Cat gen shelled out in a different camp for the same reason wrong oil. Cat decided that the 10W-30 oil wasn't the best idea so they changed the oil in the primary back to the 15W-40, they did not change the oil in the secondary. Fast forward 200 hours or so. Again in the middle of the night with 40 below temps outside (inside it would be 70 at the ceiling and frost on the floor at the building joints) the water pump failed on the primary they just changed shutting it down. Same procedure warm the secondary then switch over. The problem was that the secondary, full of the 10W-30 wasn't running right. I called the Cat dealer to deal with the primary and the service company to make an emergency oil change on the secondary. The mechanic on the primary said it needed a water pump, didn't have one, would have to go take the one off of my shelled out original primary, went to go do that. The service company finally showed up to change the oil in the secondary, which was running worse, changed the oil which at that point didn't help. The Cat mechanic showed back up about the time that the secondary was showing signs of shelling out. The Cat guy and the service people wanted me to shut down the secondary in -40 temps to keep the engine from destroying itself more than it was already. The cat mechanic said that he could have the new water pump on in an hour and a half. I told him that he better get going, I let the secondary run for a little while longer then shut it down. Dark camp with no heat 40 below out side. It took about an hour and 40 min to get the primary up and running by then it was down to 50 degrees inside which is about the point that one has to call for an emergency evac to a warmer location. The bottom line use the oil that your engine was designed for. Saving a few pennies or experimenting cost major rebuilds of 3 Cat engines and could have cost someone their life. End of the story there wasn't a replacement for the secondary so the second primary with about 3500 hours ran 24/7 for a month and a half with the correct oil in it only stopping for very short maintenance with it's dead sister sitting next to it until the camp was shut down. That is what they should have done in the first place with the correct oil. It wasn't the oils problem it was the viscosity of the oil.

That demo with the grad cylinders was great. Thank you.

part of the issue of changing viscosity is also the oil pumps flow rate and pressure relief valve. if you use a thinner oil then you could end up with low oil pressure at low revs. if you use thicker the pressure relief valve will bypass and reduce the flow around the engine.

very cool engine cutaway!!

I know Ford recommended 5w-20 on the 5.4s. I switched to 5w-30 at 178k. It sounds so much better. IMO thinner oils work great at 100k or less miles. After the engine gets some wear on it then i would go up slightly in viscosity.

You will need a different weight oil depending on your location. Think UAE vs Alaska. Most manufacturers recognize this.

10W-40 was recommended in my vehicle's owner manual and I am using 0W-20. Driven 20k miles. It's been almost 3 years, no issues. 😎

Very instructive video!

Back in the day when I was a Ford tech, Ford training classes always stressed that 90% of engine wear happens at cold start. So they want an oil that will come up to pressure quickly when started.

As any land Rover discovery 2 owner knows, you MUST ignore the factory recommended oil and switch to Rotella 15w-40, as that engine almost requires it. You might say "oh, the factory knows best." But, Land Rover...

I was waiting for you to discuss oil shear in race/ track scenarios.

synthetic vs non-synthetic , that's also a changing point in these oil numbers, stick with the specified grade that the car is designed for 👍👍

The last few minutes explained it all simply for me to understand. Thanks.

3:31..Q Jet baby! Easily the coolest sounding secondary howl ever!

The best aspect of this presentation is clarifying that the two parts of the multigrade designation are not about WInter vs. Summer (although I think that was the origin of the 'W'), but Cold Startup vs. Hot Operating. HOWEVER, there's a catch with manufacturer's recommended viscosity. When running the EPA fuel economy test they look for every possible legal edge to improve the results (because marketing). One of those tricks is to test drive with thinner than optimum oil viscosity. BUT, they are then legally obliged to make that grade their official published recommendation (i.e. your owners manual). That is why I don't worry about running slightly thicker in summer. My OM recommends 0W-20 and I have no concerns running 0W-30 in summer.

Great summary. Thanks for sharing. 🤓

BMW recommended 5W 20 in my engine....but they also recommend long service intervals. The reason they do this is both emmissions and costs of serving during the first 3 years...so they can say its cheap for fleets to run.... I serviced it every 9000 miles and at 80k put 5W 30 in it...its now at 245,000 miles...I guarantee it wouldn't be had I used the oil BMW stated and changed it at it's service intervals.

This is why I like my engine, the manufacturer specifies thicker oil for extremely hot climates, thinner oil for very cold, and one in the middle for moderate climates which is most places on the planet.

This was awesome. Thanks!!!

Sir you are brilliant, love to hear you talk.

Absolutely correct, my car recommends 5w-30, but in Michigan during winter I swap to 0w-30 to help with cold start wear 🤙🏻👏🏻

It’s amazing how these manufacturers are able to protect engines with such low-viscosity oil.

Thank you for adding Vietnamese subtitles to this video ♥️

loved it! Great explanations

"Thinner oils are more efficient" S54: *Sweats*

The real question is: can a high mileage car run on the same oil grade than the one when it was new? Do climate play a role in oil viscosity?

Very informative. Thanks.

Looking at these new engines makes me Soo happy 😊

Over 35 years ago, I was studying electrical engineering in Kingston UK. We were lucky enough to have two lecturers with a boundless depth of subject knowledge and were equipped with the means to communicate that knowledge. I said at the time that as students we were enjoying a charmed education. Your presentation and communication skills mirror those days. Fantastic! Oh! And one more thing, thanks. Mike. RIP Tom S.

I went from 0W20 to 5W30 into VW 1,5 TSi engine with 2 cylinders deactivation. Our local weather is from -20 to +40 degree Celsius, and I believe 5W30 is the sweet spot. Car manufacturers are pressured by the EU to push the emission down so they put the low viscosity motor oils int their engines.

Loved this video. Did MOBILE ONE mention that the price of gas has gone down and the cost of oil has almost doubled in the last year.

Thanks for the important info 👏👍

Did your homework man, glad to see someone telling the right things