Will Thinner Oils Damage Your Engine?

Hello everyone and welcome to this video sponsored by mobil1. They've given me access to their

engine

ering teams, so we'll focus on three questions about motor

oils

. What do oil weights really mean? Thinner

oils

improve fuel efficiency and can thin the oils. Effectively protect an

engine

. Now next to me is a cutaway of the 6.2-liter V8 engine found inside the C8 Corvette. This engine comes equipped from the factory with a moving one and I'm going to use that to help and explain how oil interacts with

your

engine, so let's start with oil weights and what these numbers really mean.

Now, right away, we need to clarify something: the term weight is not so appropriate, since these numbers do not represent a measure of weight but rather a measure of viscosity. So what these numbers really identify is the viscosity grade of the oil. Viscosity is essentially the thickness of the fluid. A thicker fluid like honey

will

have a higher viscosity than a

thinner

fluid like water. Ensuring proper viscosity is the most important criterion of a motor oil and the higher the viscosity grade in the bottle the thicker the oil, but these numbers also depend on temperature, so for example here we have a 10 w30 oil, the first number 10w w that represents winter represents the degree of viscosity of this oil when it is cold, the second number 30 represents the degree of viscosity of the oil when it is hot because there are two different numbers here.

It is now called multigrade oil, since the second number is greater than the first. Does this mean that this oil becomes thicker as it is heated? No, it just means that he behaves well. like a thicker grade oil at sae 30 grade when it's hot but it behaves like a sae 10 grade when it's cold here's a quick demo so in this cylinder I have 100 milliliters of 5w30 at room temperature and then in this cylinder I have 100 milliliters of That exact same 5w30 oil, except it's been in the freezer overnight, so I'm going to put a ball bearing in each cylinder and whichever one reaches the bottom first, that

will

be the most diluted fluid.

I hope it is messy, as beautiful as you can make it. See the cold cylinder here with the cold 5w30. It took much longer for that ball to reach the bottom, so as the oil heats up, its viscosity decreases. If you look at a graph of temperature versus viscosity it will look like this, so in blue we have a 0w40. oil like you find in the corvette and then our redline is a 10w30 and what you will see is that in cold temperatures the 10w30 is thicker; However, as that oil reaches operating temperatures, the 0w40 is thicker and both oils continue to thin as the temperature increases, so how does one oil behave as different grades depending on temperature?

Well, you generally start with a low viscosity base oil and then use additives, specifically viscosity modifiers, to change that rating as the oil warms. Now let's go back to our 5w30 oil. and talk about how it is classified as 5w30. Both numbers have multiple tests at multiple temperatures to certify the rating. Cold rating includes tests ranging from negative 10 degrees Celsius to negative 40 degrees Celsius and in these cold temperatures you are looking for. For two things, first, can the engine actually start? When cars used carburetors and distributors, you needed a fairly high cranking speed to start the engine.

If the oil was too cold, it could prevent the crankshaft from turning fast enough and actually prevent you from starting. The car now, modern fuel injected cars can start at lower cranking speeds, but you still have to make sure the oil is thin enough for the oil pump to pick up and circulate through the engine, so that the second part, if the car starts, it must. make sure the oil is actually flowing if the oil gets too cold wax crystals can start to form and it starts to form a structure instead of acting like a fluid obviously if you don't have oil flow you are not protecting

your

engine , so it is essential to have a test that ensures that at low temperatures the oil does not thicken too much.

Now the second part of the 30 rating is based on viscosity measurements taken at 100 and 150 degrees Celsius in these high temperature tests that we are analyzing the oil. flow when it comes to seal leaks, which can affect oil consumption and we are looking at the viscosity of our oil when it is forced to form a very thin oil film, such as with bearings, the interaction of the piston cylinder and camshafts, now as to what contributes in general to the viscosity rating and of course it depends on what this rating is, but generally speaking, the cold rating depends more on the base oil that is used. uses and then hot sorting will depend on the additives like viscosity modifiers, now maybe you have noticed. a trend in the automotive industry where these numbers keep getting lower and lower and in fact production cars are sold today with zero w16 motor oils, so why are they doing so well overall, The lower these numbers are, the better the engine efficiency will be?

This is an industry where efficiency is everything now, can they continue to protect at the same levels as thicker oils? We'll address that question a little later in this video. So why are

thinner

oils more efficient? Well, it basically comes down to friction, if you think about it. about dragging your hand across a surface of honey is slow and difficult to do if you think about dragging your hand across the surface of water, it is easier and requires less energy to do it, the same idea applies to oils that act as a protectant. barrier between two surfaces but of course there is still friction between the metal surface and the oil, the question is how much the efficiency can actually be increased with the obvious disclaimer that it depends on many things such as what viscosity grade we are comparing with another. motor we are using, what the operating conditions are, etc., but I have seen studies that show that going from 30 to 20 could result in an increase of more than 1 in efficiency, as well as going from 20 to 10. yes Look at the fuel economy tests.

Lower viscosity grades are required to meet more challenging fuel economy limits because they are known to improve efficiency. Based on these fuel economy tests, you can get the benefit of a 0w or 5w20 over a 5w or 0w30 within 0.3 percent. to 0.5 percent and the benefit of a 0w or 5w30 over a 10w30 is in the range of 0.2 to 0.7 now striving for a fraction of a percentage improvement in fuel economy may not seem significant to those who They don't work in the field of internal combustion efficiency, but when you consider how efficient today's engines are, gasoline engines with a maximum efficiency of around 40 percent, increasing that number to 41 is a very difficult problem. to solve and oil can help play a role in the solution, I understand that fuel efficiency is not.

Everyone's favorite topic, but I have to admire the challenging problem that engineers face and the solutions that result from addressing this problem, so the big question: can thinner motor oils effectively protect an engine? I've asked quite a few powertrains this question. The engineers and I discussed it with mobil1 and with modern engines, engine wear is usually not a limiting factor. Companies have done a very good job of figuring out how to make internal engine parts last. What is more challenging is improving fuel economy and how this can be done. As you move to more diluted oils, companies are doing this, I think it's worth understanding how wear occurs so you can better realize how more diluted oils can still protect engines from wear, as long as you use the oil to the one your engine is designed for.

You'll find it in your owner's manual and we'll look at some exceptions. Engines don't really have metal to metal contact, you simply have oil between the moving metal surfaces and as long as your oil pump maintains proper flow and your oil is in good shape and with changes at regular intervals, there won't be much. metal wear. Now there are cases, like when you start the car, where you will not have the full thickness of the oil film available between the moving parts, that is when anti-wear additives are needed. useful that adheres to metal surfaces and minimizes wear on startup.

There is also something very interesting that happens with the pistons and the walls of the cylinder, so you have oil sprays that line these walls to protect this piston as it moves up and down and as that piston is moving, it is protected by that barrier, that film of oil, however, the piston is not always moving, so when it reaches the top it changes direction and for a brief moment the piston stops and then when it reaches the bottom bottom again, change. direction, so for a very brief moment you are not moving As an analogy, think of a person sitting on water skis in about a foot of water, so if that person is not moving well, then their water skis are resting on the sand beneath them, beneath that foot of water. but once the boat starts pulling them, those water skis appear above the surface, the water does not have a super high viscosity, but still, when your speed increases, you appear above that water and inside your engine once you that piston starts moving up or down again, it appears on that film of oil for the vast majority of your engine, it has a high speed between the moving metal parts and that high speed keeps the parts floating on a film of oil preventing wear, that means you just have to go out, buy a more diluted oil, and stick it in your car.

No, your engine was designed and validated using a specific oil, verifying that the engine had acceptable engine life and durability, desired fuel economy, and met an acceptable oil drain interval. I always should, always, always did. Let's say it's always enough, use what is recommended in the owner's manual, but let's have fun with some hypotheticals that, again, you shouldn't do at all. This motor uses zero w40 mobile motors, so what happens if you put 0w20 in it? It would probably be bad. Higher performance engines will see this. higher loads on engine parts and may need a higher viscosity for a more robust oil film.

You may have too much bearing leakage if you used a diluted oil, so as a general rule, lowering the rating number while hot is a bad idea. but what if it was thicker with hot sorting? Well, generally speaking it's not terrible, although again it's not recommended in specific cases where a car spends a lot of time on the track and the oils reach much higher temperatures, sometimes you'll see cars recommend a thicker viscosity. degrees when you're on the track to make sure the viscosity is still high enough at those higher temperatures. Now, what would happen if you lowered the first number?

So, let's say your car recommends a 10w30 and you put a 5w30 in instead, if you look at the general viscosity range of each of these different grades of oil, you'll see that the 5w30 range falls completely within the 10w30 range, so What really the engine would not see a viscosity that it has not seen before, but if it were for the In the opposite direction, let's say your car recommends a 5w30 and you put a 10w30 in it. So at cold temperatures you will see a much thicker oil, so you could have cold starting and oil pumping issues, so the ultimate rule is to use what the manufacturer recommends.

If you use a higher number here or a lower number here, bad things can happen if you use a lower number here or a higher number here it's not as risky. Have I said it enough times? How many times have I said it? Use what your car manufacturer recommends, hopefully We've all learned a thing or two about oil and how great this engine is 6.2-liter naturally aspirated V8 engine 495 horsepower 470 pound-feet of torque Fuel system dry sump oil Cylinder deactivation Equal length intake runners Swept up exhaust manifold It's a A great engine sounds phenomenal and is a pleasure to drive.

Many thanks to Mobile One for sponsoring this video and providing access to their engineering teams. Check out the link in my video description to find Mobile One in a car zone near you. Thank you all. Too much to see, if you have any questions or comments feel free to leave them below.