Can someone give me a website to help explain oil and how it thins out etc

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Im trying to explain to someone at work how oil works etc, so say you have a 5w40... I was saying it starts off at a thinner 5w and once up to operating temp is ends up at a 40w. Then he was saying well it thicker cold and thinner hot, so how does it do that and so on. I tried to explain VIIs etc... Can someone give me a website or something to print out to give to him. Id appreciate it! This is the only place I knew to ask for help lol.
 
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First off, oil always thins as it heats up and does not start out thinner and then thicken. There is no "5W" that it starts out as, 5W is a winter performance rating that the oil meets. What you described is what you will find a lot of websites saying but it is not correct. Multi-vis oils thicken less when cold than a straight grade but they still thicken. A lot.
 
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From my internet reading, and I may be wrong, but I always thought one of the additives they put into (multi-viscosity) oil was like small coil springs (for lack of correct word). When these coil springs get hotter, they start stretching out which thickens the oil. When oil gets used, it shears (lower viscosity), because these coil springs are getting chopped-up in your engine (cams, timing chain). Edit: 5w-40 would start out as 5 and thicken to 40 once engine is at operating temperature.
 
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Originally Posted by MasterSolenoid
Edit: 5w-40 would start out as 5 and thicken to 40 once engine is at operating temperature.
I don't think oils thicken when hot. They only thin to what a 40wt would when hot, as opposed to when they're 'cold' they are only as thick/pumpable as a 5wt. In other words, the VII's prevent them from thinning as much.
 
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Here, this isn't bad: http://www.elf.com/en/advice-corner/engine-oil-faq/oil-viscosity-chart.html and to clarify my earlier post, yes there is a 5W performance or viscosity rating but what I was trying to point out is that it isn't as if the oil starts out at an SAE 5 and thickens to an SAE 30 (or whatever) when hot. First off there is no "SAE 5" oil (just as there is no SAE 0 oil) and secondly no oil is thicker hot than cold. In a lot of ways I've always thought it is unfortunate that the winter rating is expressed as a number because that leads to confusion. One could just as easily list the winter rating as a letter such as AW-30 or BW-30. At least that would eliminate people thinking the oil "starts out at a 5 and becomes a 30 when hot".
 
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Engine oil gets thinner as it gets warmer. Many engine oil PDS's will indicate the viscosity at 40 c and 100 c the value for 100 is always lower. Here is an example of Mobil 1 5w30 https://www.mobil.com/English-US/Passenger-Vehicle-Lube/pds/GLXXMobil-1-5W30 At 40 c the oil is 61.7 cSt At 100c it is 11 cSt The most important viscosity measurement is HTHS high temp high shear HTHS Viscosity, mPa•s @ 150ºC (ASTM D4683) Which is 3.1 for this oil. Oil does not ever thicken as it warms. It may thin more or less. This is the function of viscosity index. Many people look at is onsite index as a quality. But bigger is not always better.
 
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It doesn't start as a 5W and end up as a 40 weight. In laymen terms, it starts at like a 600 weight, and as it heats up, it thins to a 40 weight at 212 degrees operating temp. Oil at room temp or colder is WAY too thick for an engine. It quickly heats up and thins out to the proper 30 or 40 weight that the engine needs.
 
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For clarity & brevity, I like the viscosity graphs at ________________________________________ https://wiki.anton-paar.com/en/engine-oil/ ________________________________________ For example, between the freezing point of water (32F = 0C) and boiling (212F = 100C), you can see a typical 5w40 oil gets thicker fast when getting cold: [Linked Image] Other graphs are shown for other weights, like 0w-30, etc. Those charts are representative, and there are some brand variations on the exact curves. Close enough. Those red lines on the graphs flatten out a bit as you go down in "winter" weight, the "xW" part. One important thing to know: VII (visc index improvers) actually thicken a base oil when hot, over what a pure base oil gives you, and has little effect on cold properties, so that if you want to formulate a good 0w-30, you have to start out with pure base oils that are thin, and then add VII enough to get it thick enough when hot.
 
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Eventually oil will thicken with heat. Any volatiles will be gone and whats left will coke up. In my prior life I did some lab testing with asphalt bitumen on this very subject. For lack of a better term, oil is thermoplastic.
 
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Originally Posted by NattyBoh
.. Can someone give me a website or something to print out to give to him. Id appreciate it! .
I wish people answering this thread would answer what was asked. .... I would suggest printing out the 0w-30 and the 5w-40 graphs from the Anton-Paar website I cited above, and showing how the red line flattens out. That explains how an oil behaves, and the difference between a 0w and 5w oil when cold or cool. https://wiki.anton-paar.com/en/engine-oil/
 

NattyBoh

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Originally Posted by oil_film_movies
Originally Posted by NattyBoh
.. Can someone give me a website or something to print out to give to him. Id appreciate it! .
I wish people answering this thread would answer what was asked. .... I would suggest printing out the 0w-30 and the 5w-40 graphs from the Anton-Paar website I cited above, and showing how the red line flattens out. That explains how an oil behaves, and the difference between a 0w and 5w oil when cold or cool. https://wiki.anton-paar.com/en/engine-oil/
Thanks!! And sure as a ten year vet, I honestly never grasped the science on it much as you can see... Then let me ask this. I thought 5w-40 oil was a 5w at cold temps to help lube quickly, get oil psi up faster etc? Then once it was at operating temps the oil would be a 40 weight due to the VIIs? They would expand when hot.
 

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Originally Posted by NattyBoh
Then he was saying well it thicker cold and thinner hot ...
Yes, basically every liquid on earth gets thinner as it heats up. The oil viscosity rating numbers are at two different temperatures. There is no connection between the first "W" (cold rating) and the last number (hot rating).
 

NattyBoh

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Originally Posted by ZeeOSix
Originally Posted by NattyBoh
Then he was saying well it thicker cold and thinner hot ...
Yes, basically every liquid on earth gets thinner as it heats up. The oil viscosity rating numbers are at two different temperatures. There is no connection between the first "W" (cold rating) and the last number (hot rating).
Ahh. I know it gets thinner as it heats up but then.... whatever lol Im confused on how it goes from a 5 weight to a 40 weight. Or it doesnt? Then why use a 5w40 for cold temps , to improve/help cold starts right? Because the film strength/weight is lower when cold?
 
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Originally Posted by NattyBoh
Then let me ask this. I thought 5w-40 oil was a 5w at cold temps to help lube quickly, get oil psi up faster etc? Then once it was at operating temps the oil would be a 40 weight due to the VIIs? They would expand when hot.
All true. The VII's do help the thin base oils be thick enough when hot to satisfy requirements to be a "40" hot. The VII's don't get all the credit, but they help thicken the oil when hot, yes.............. The "5w" designation means it is tested at -22 degrees fahrenheit to be thin enough to earn the 5w rating, indicating the oil doesn't get too thick when cold. (A "0w" oil has to be even thinner when that cold.)
 
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