What are the main differences between grease and oil?

Grease and lubricant are often used in the same applications (gears, bearings, etc), but the two behave very differently and have different use cases.
Here at Lubrication Expert we take a first-principles approach to lubricants and greases; helping industry understand lubrication technology and pushing the limits of what is possible.
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[@LubricationExplained]

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[@georgehofgren6123]

Um, It seems as if you didn't mention the most important variable... the speed of the bearing. The oil or grease needs to "flow" not just to carry heat away, but it also needs to flow Into the bearing quick enough to keep up with what's being pushed out. At higher speed, the grease will not be able to keep up with the rollers and cannot be replaced, unlike the oil which can remain around the rollers. Granted, there is oil in grease, but over time and with heat, that oil separates out. Anyway, just seems like bearing speed is a determinant to thickness ~

[@LubricationExplained]

Great point! As you can probably see from the date of the video this was one of my early ones and the quality wasn't exactly... as I wanted. Haha. You're absolutely right that I missed the big one.

[@cbremer83]

A little real world example of the oil flow heat transfer is in rotary engines. Most piston engines do not have dedicated oil cooling unless it is a heavy duty or high performance application. Rotary engines are a little bit of a special breed, though. Only the outer edge of the motor is cooled by the water pumped through it. The whole center core of the motor is only oil cooled. And the oil is forced through it. Using an Mazda RX8 as an example, this oil pull about 1/3 of the overall heat from the motor and dumps it through two massive oil cooling radiators in front of the front wheels. These two cooler are nearly half the size of the water radiator. Not sure if anyone will find that interesting or not, but I figured I would share it as an easy real world example of that part of your video.

[@LubricationExplained]

Wow! Thanks for sharing!

[@peacefulwarrior4078]

Grease is basically oil that has a thickening agent added to it which then makes grease .and as that grease gets older it gradually drys up leaving no oil but only the thickening agent left in the bearings . Hence the need to clean out the bearings and repack with fresh grease💪😎👍

[@pazzy4501]

Well done, best info and best explanation, keep up the good work 👍🏻

[@heshamalam7193]

An excellent video. It would be helpful to have a comparison video of Ca, Na, Li and Mo based greases. Thank you very much.

[@LubricationExplained]

How do I choose what type of grease thickener to use? kzbin.info/www/bejne/qIS4q317i71jlZo

[@fedo9644]

Thanks a lot, i'm going to use that info when greasing my skateboard bearing

[@patelikram2898]

Very good explanation. Very good channel for learning about lubrication. Request to make full course on used oil analysis.

[@LubricationExplained]

Will endeavour to do so! There are so many topics to cover!

[@victororozco7727]

I love your channel, I was thinking I get my answer and I did but I love how I have more questions!

[@ejazahmednaqeeb]

Excellent Voice and a very Good Video

[@LubricationExplained]

Thank you kindly!

[@heshamalam7193]

Many large equipment have electric motor driven auxiliary oil pumps to circulate lube oil prior to start up. Once the equipment is running the directly driven main oil pump takes over and the aux. Oil pump stops as per instrument and electrical logic diagram.

[@rickc2222]

Just repacked my trailer wheel bearings (non-sealed tapered roller) and there's a nagging question I've often wondered. I googled it and could not find an answer. Essentially - I can't help but think that the rollers will just push 99% of the grease out of the way, and the tiny bit of grease film left on the races and rollers should degrade and bearing fail in short time. Obviously that is not what happens... So i guess i am asking how the heck does the grease do its job? does it turn liquid when warm and flow around the bearing, giving it fresh grease constantly? every time i have repacked a bearing i see a big ol blob of brand new grease in the middle doing nothing and then a small amount of dirty used grease around the bearing, so it can't be flowing much... Timkin says pack the hub 1/2 full of grease. Does the centrifugal force cause the grease to flow a bit and push itself into the bearings? So many videos of guys doing it wrong, only packing the bearing and not the hub - will those likely fail prematurely?

[@selfelected3832]

To be quite honest, I have no idea what kind of lubricant to use. For 88mm Bearing Cable Pulley Wheel Aluminum Alloy Gym Equipment, what is advised? I recently acquired some weight lifting equipment, but the factory-installed pulleys were broken, and I didn't feel confident using them, so I ordered some new aluminum pulleys. Any help would be very appreciated as I'd like to keep them maintained so they function without much to no resistance.

[@RaZhanBreonna]

Using this information for my hair 🤣😊😂🤞🏽. Definitely going back to grease, thank you !

[@LubricationExplained]

You’re welcome 😊

[@Boodoo4You]

“G’day everyone”. That’s an instant like for my Aussie brother.

[@fyahwerks]

When you have time do a feature on the different types of grease

[@LubricationExplained]

That’s the plan!

[@joseduranjr4963]

I’ve always used 2oz of transmission fluid in a fresh oil change and a tablespoon of grease in the filter. All my engines have lasted more than 500,000 miles.

[@rafaelcruzmenezes6009]

Very good

[@LubricationExplained]

Thanks!

[@hillbillyjim375]

Thanks on behalf of my tools

[@aminechelghoum5286]

Sir Can u make a vedio how u make the grease

[@elitegaming2032]

Do grease evaporates on the hot weather?? 30C to 40C° Temperature?? Please let me know sir..

[@LubricationExplained]

No - at 30-40C you wouldn't see evaporation. Bearings typically run at 60-70C and greases can operate for years in this temperature range.

[@drnavinkiranmurty8458]

Pl share some videos on grease

[@LubricationExplained]

Trying to put a few together on different grease technologies but there are so many topics to address, please be patient with us!

[@monishreddy4466]

Sir, I have a question. I am new to this topic and i dont really understand why it takes 10-20 seconds for the lubricant to reach bearing

[@LubricationExplained]

Good question - in some instances it may just be that the bearing is at a high point, and far away. It being at a high point means that when the pumps are off, the lubricant drains back into the reservoir, therefore there is no lubricant at the bearing. On startup, the pump has to move a volume of lubricant to the bearing - if the lines are long, it could take 10 seconds or so.

[@monishreddy4466]

@@LubricationExplained understood.. thank you sir

[@hojoongkim1435]

In really dusty environment which lubricating would be better? I mean between oil and grease.

[@LubricationExplained]

If there is no way to prevent the contaminants from reaching the application, then in a REALLY dusty environment you probably want oil, with a REALLY good filtration system. Grease is really good at keeping contaminants out, but once the contamination gets in, it stays in until you purge the grease. Whereas oil can flush through the application, taking contaminants with it. The oil will only be as good as the filtration system thought!

[@mr.gutwrench]

Ball and roller bearings are supposed to roll in there races, does the lubricant ever cause them to slide instead of roll? and wouldn't that be a bad thing?

[@LubricationExplained]

Yes! That can absolutely happen. Overgreasing a bearing, or using a viscosity that is too thick can cause churn, and can cause the rolling elements to slide.

[@paulsawczyc5019]

They all slide - because the outside diameter travels more distance than the inside bearing race.

[@JunkCCCP]

​@@paulsawczyc5019nobody tell this man about planetary gear sets

[@drnavinkiranmurty8458]

What u mean by leakage in grease ?

[@LubricationExplained]

Leakage of grease could mean a couple of things. Firstly it could be that the dropping point of the grease has been reached - this is the temperature at which the base oil is released by the thickener. Secondly, if the grease is too soft (too low an NLGI grade or the thickener has sheared over time) it will "flow" out of the application.

[@torstenB]

I got your video proposed and next to it an ad for KFC. Sometimes AI works all too well 😂

[@jamesyarbrough4777]

how are things going over there? ive read some scary stuff about lockdowns and martial law

[@LubricationExplained]

Yeah to be honest probably not as bad as is being portrayed in the international media. Sydney is in lockdown at the moment but I think the term "martial law" would be a stretch. We're still able to go outside, all essential services are open, and the main rule is that you're only allowed to go to work if your work cannot be done at home, and in certain parts of Sydney you must wear a mask outside. So construction activity continues, etc. there's just no one in offices in the city. It's still devastating for a lot of non-essential retail and tourism, but it's not like the army is rolling in with tanks.

[@mikeadler434]

👍👍

[@dnbarracus]

❤

[@TheClintmeister]

My thoughts on grease. It can't be cleaned. It causes more friction. It's hard to replace where it is located. And for last just now they are developing "better" greases.

[@LubricationExplained]

True. But in some instances there really is no good replacement. There are some methods for filtering greases, but they're really only economic if you're using grease in massive quantities.

[@cipaisone]

Grease cause more friction? What do you even mean? Under proper conditions, greases very effectively lubricate contacts. In some cases, their semisolid nature is a great advantage., if not a requirement Think for example of flange lubrication, in rails. The lubricant must stay at the wheel flange - rail corner contact, and greases are naturally suited for it. Grease are not “bad” and oil “good”. There are applications where one or another solution ( or neither of the two) is more suitable .

[@bestamerica]

' grease is a good to use gearbox but little leak spread outside... oil is a not good in gearbox and can leak spread outside

[@ahndeux]

Oil also has lower viscosity than oil. If you have bearings that need to spin faster, you need a lower viscosity lubricant. You can't use grease in these applications. Another important factor is application dependent. On fishing reels for instance, the spool bearings need to have very low friction in order to reduce the drag the bait has to swim against when it's pulling line. Using grease would increase the resistance and cause the bait to not be able to pull out line from the spool properly before it tires out. The lower friction on the spool also makes casting easier and improve the distance on the casting. On fishing reels, the spool bearings are usually lubricated with oil instead of grease to reduce the lubricant drag. In fact, some reels uses a very thin dry film of lubricant to make the spool spin with very little friction. Even oil in these applications would cause too much friction. You will have to lubricate more often over a season, but it improves the performance. There are lots of other examples where one type of lubricant is superior to others.

[@jordanhowe117]

I'm just here to quiet a door hinge

[@LubricationExplained]

No problem too small!

[@BassicVIC]

Well. Grease is the word, it’s got groove, it’s got meaning. Oil not. Grease is the time, is the place, is the motion. Oil isn’t.

[@WynnBG]

U sound like Technoblade

[@LubricationExplained]

Hahaha, funnily enough you're not the first person to say that.

[@hothmobile100]

Love your videos for the content. Your visuals/graphics are extremely good but your microphone sucks. You should buy another microphone with all that money you save on single payer healthcare. ('m in USA).

[@LubricationExplained]

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