Help me understand oil weight.

[enkeivette]

My UTI buddy told me that the w stands for winter, not weight. So if 10w 30 means 10 winter, 30... I'm confused. Obviously the higher the number is, the thicker the oil, but then why would it be 10 winter? Not 30 winter? I would think 10 would be the hottest temp viscosity and that the oil wouldn't get thicker than 30 during the winter.

[94cobra69ss396]

My UTI buddy told me that the w stands for winter, not weight. So if 10w 30 means 10 winter, 30... I'm confused. Obviously the higher the number is, the thicker the oil, but then why would it be 10 winter? Not 30 winter? I would think 10 would be the hottest temp viscosity and that the oil wouldn't get thicker than 30 during the winter.

He is correct. I got this from Castrol's website:

The API (American Petroleum Institute) symbol on motor oil labels is also called a donut. It unlocks a lot of cool and critical information that can help you choose the ideal motor oil. Let's nibble away at the donut to understand its true meaning.

Top of the Donut – Performance Level Indicators
See the two letters at the top? The first signifies engine type. If you see an "S," that oil is designed for gasoline vehicles. A "C" means diesel. The second letter represents quality. For the most protection from power-robbing deposits watch that second letter. The higher it is, the higher the performance quality. "SM" is tops for gasoline engines.

Center of the Donut – Viscosity Grade Identifiers
Right in the middle is where you can focus on viscosity, which relates to oil flow at different temperatures. Look for the SAE (Society of Automotive Engineers) mark. The lower the number on the left, the thinner the oil at low temperature, and the happier your engine will be in cold weather when it's time to turn over. The number to the right relates to higher temperatures. Higher numbers indicate thicker oil for better performance in the heat. The "W" stands for Winter Grade.

Multi-grade oils carry a dual-viscosity grade so they perform well in high or low temperatures. Now when you see identifiers such as 10W-30, 5W-20 or 20W-50 you'll know what it means – winter on the left (go lower), summer on the right (go higher).

Bottom of the Donut – Energy Conserving Properties
Down below, oils with fuel-saving ability that pass standard industry tests are labeled as Energy Conserving. With rising gas costs, it's nice to know if your motor oil also provides fuel economy benefits.

[Vettezuki]

The old guy (forgot his name) who owns this company will absolutely talk your ear off about the history of lubricants/oil and how much "snake oil" is involved in the marketing of said. Especially American made Mobil One synthetic. As I recall the main thing is that while it's highly temperature resistant, it easily becomes very acidic and causes premature bearing ware. Talk to him and you'll get an earfull of TBN this and Ph balance that . . . be prepared. I should have taken notes, because it's gone a bit fuzzy.

http://www.gopurepower.com/

The bottom line here for most of us, about the best oil you can get before going to the custom Gucci blended stuff is cheap and easy Rotella (Shell) 15/40. If you buy it in a 5gal drum it's less than $3 a quart.

[enkeivette]

But why would the oil be thinner (10) in winter temps than in summer temps (30)???

Ben, very interesting. You run cheap organic Shell oil? I'm a firm believer in synthetics, but I have heard some negative things about Mobil 1. I might go with Royal Purple or Redline in the vette after break in. I put so few miles on it I could prob change the oil once a year without it getting dirty, and I've heard that synthetics don't break down after time, so mileage is more important than the length of time it sits in your oil pan. Right now I'm using Valvoline.

[Vettezuki]

But why would the oil be thinner (10) in winter temps than in summer temps (30)???

Ben, very interesting. You run cheap organic Shell oil? I'm a firm believer in synthetics, but I have heard some negative things about Mobil 1. I might go with Royal Purple or Redline in the vette after break in. I put so few miles on it I could prob change the oil once a year without it getting dirty, and I've heard that synthetics don't break down after time, so mileage is more important than the length of time it sits in your oil pan. Right now I'm using Valvoline.

There is no such thing as synthetic oil per se. It's processed from natural oil. Mobil One (American) is just about literally made from paraffin as I recall. Yes I run the cheap industrial stuff and maybe change a little more often. The engine runs noticeably a bit smoother and quieter (rockers are less noticable). But as the old timer described the important factors are things like quantity of TBN (as I recall) and the actual ph balance of the oil, these are the actual lubricating and non-wearing petro-chemical attributes you need to be concerned with. I'll need to hit him up again, or find actual tech articles.

The winter summer thing is really only a short hand for thermal viscosity (weight @ temp); it corresponds to objective viscosity within objective temperature ranges, the details of which I don't recall. Dig through SAE docs for gruesome detail somewhere. YES, the multi-grade oil gets "heavier" as the molecules unwind with temperature. Easier for startup, heavier protection for operation.

Here's a quick easy read (just scanned) on weights.
http://www.aa1car.com/library/oil_viscosity.htm

Sorry I can't be precise, I remember "about" the issue but not the details.

[enkeivette]

Very skeptical of this, I'm not a chemist but I can tell you that hot oil is thinner than cold oil. I've seen & felt them both.

[kdracer73]

Very skeptical of this, I'm not a chemist but I can tell you that hot oil is thinner than cold oil. I've seen & felt them both.

I totally screwed that up !!:bang: Had not had my coffee yet. Had to delete it to hide my shame . .

[Leedom]

Nice short explanation. How Stuff Works! (http://auto.howstuffworks.com/fuel-efficiency/fuel-consumption/question164.htm)

[SeanPlunk]

What kind of oil is everyone using?

I used Mobil 1 on the Camaro, but I'm using Royal Purple on the Cobra now. I've thought about using Amsoil next time though. Opinions?

[SeanPlunk]

I totally screwed that up !!:bang: Had not had my coffee yet. Had to delete it to hide my shame . .

LOL, don't feel too bad - I brought two left shoes to work today :thumbs_up:

[Vettezuki]

Rotella (Industrial purpose 15/40 Shell Natural Oil)

[BRIAN]

I'm going to throw my .2 cents in here, I'm no expert so please disagree with me if you get that gut feeling. This is all from research and experiments I've done in high school and a little in college.

First of all oil viscosity is different for all oils for the most part. Like shoes for example, a size 10 Nike isn't the same as a size 10 Puma. Likewise, 5W-XX from Mobile one isn't the same as a 5W-XX from Redline. I just wanted to touch on that with you guys really quick. Here is a chart for quick reference.

http://img121.imageshack.us/img121/7533/oilviscositycomparison0.gif (http://img121.imageshack.us/i/oilviscositycomparison0.gif/)

Alrighty now, so in case some of you didn't know we have 5 base groups of oils, groups I - V is how they go. Now today's oils in your local auto parts stores pretty much carry group III hydrocracked oils, aka out of mother earth. Group 1 I won't even mention but groups II's are those single weight oils you see on the shelves, nothing special there, it's break in oil if you want to use it I guess. Group III base stocks are the same as II's except we have many more viscosity's....SWEET RIGHT, we love choosing 5's and 10's and for you crazy people the 20's!!!! LOL okay so then we move on to the good stuff.

Group IV base stocks are polyalphaolefins (PAO). These were the 1st synthetic oils produced, example would be German Castrol European Formula, bitchin oil for the price, I put 12k miles on it no prob. Group V base stocks are for the most part poly esters (POE), quick example of that is Redline, superb oil but ehh $10 bucks a quart, not in my street machine. Here in the United States a group III oil is okay to be called a synthetic, not in other countries like Europe. Yep, that super cool "synthetic" penzoil oil you've been using isn't really synthetic, sorry. Doesn't mean it's a bad oil, not even close. Today's oils regardless of what you choose will run perfectly well in your motors assuming not big huge mods have been done to the bottom end. The reason i bring that up is because of the prices they charge for oil that is not a true synthetic…if I’m going to use a synthetic oil, I want to get what I’m paying for.

Just so you know I know more about synthetics than I do mineral oils for the fact that I own a turbo car. They resist higher temperatures, like in the turbo center section, before they begin to break down.

In case your wondering I run 0W-30 German Castrol in my Supra, I usually don't discuss why as most people freak when I tell them that to the point where they have to make ignorant jokes like "why do you pour water in your motor," but I will say I prefer flow to pressure. The quicker the oil lubricates my motor on cold start up the happier I am.:bigthumbsup:

[BRUTAL64]

Damn Brian, you put some effort into this. Nice work!!!:thumbs_up:

[SeanPlunk]

In case your wondering I run 0W-30 German Castrol in my Supra, I usually don't discuss why as most people freak when I tell them that to the point where they have to make ignorant jokes like "why do you pour water in your motor," but I will say I prefer flow to pressure. The quicker the oil lubricates my motor on cold start up the happier I am.:bigthumbsup:

Great post. I believe for the Cobra, Ford recommends 0w20 stock, so I'm running water too I guess :)

[BRIAN]

Damn Brian, you put some effort into this. Nice work!!!:thumbs_up:
Thanks, misinformation sucks!!!

Great post. I believe for the Cobra, Ford recommends 0w20 stock, so I'm running water too I guess :)
Indeed we are sir, which oil are your running? Does the Cobra have an oil cooler from factory?

[SeanPlunk]

Indeed we are sir, which oil are your running? Does the Cobra have an oil cooler from factory?

I'm running Royal Purple right now. I think the Cobra does have an oil cooler, but I'm not 100% sure.

[BRUTAL64]

I've been using Valvoline Racing since 1968. On ONE motor I built, I used Quaker State and spun a bearing in the first 300 miles.:(

[enkeivette]

Still don't understand why the oil gets thicker when hotter.

I read Adam's post about the polymers getting longer, but if weight it simply a measure of how long it takes the oil to flow through an orifice, I can tell you right now that hot oil comes out of the oil pan faster than cold oil.

And from Brian's chart, it also looks like oil gets thinner as it gets hot. :huh:

[BRUTAL64]

Still don't understand why the oil gets thicker when hotter.

I read Adam's post about the polymers getting longer, but if weight it simply a measure of how long it takes the oil to flow through an orifice, I can tell you right now that hot oil comes out of the oil pan faster than cold oil.

And from Brian's chart, it also looks like oil gets thinner as it gets hot. :huh:

It's magic.:rolleyes:

[enkeivette]

It's magic.:rolleyes:

You're not allowed to roll your eyes until after I fail to understand your explanation.

[Vettezuki]

Still don't understand why the oil gets thicker when hotter.

I read Adam's post about the polymers getting longer, but if weight it simply a measure of how long it takes the oil to flow through an orifice, I can tell you right now that hot oil comes out of the oil pan faster than cold oil.

And from Brian's chart, it also looks like oil gets thinner as it gets hot. :huh:

My understanding is as follows:

The polymers unwind with temperature, increasing film strength. The oil BEHAVES as though it were a heavier weight at the higher temperature.

The multi weight means that it flows as a 10 weight would at low temps and as a 30 weight would at the higher temperature. (Of course a hot 30 weight is thinner to the touch than a cold 10 weight.) This split personality is the point of a mutli-grade oil. It offers the operating temp protection of a 30 weight, but without the very thick nature of a 30 weight at start up (especially in a cold winter climate).

[BRIAN]

Still don't understand why the oil gets thicker when hotter.

I read Adam's post about the polymers getting longer, but if weight it simply a measure of how long it takes the oil to flow through an orifice, I can tell you right now that hot oil comes out of the oil pan faster than cold oil.

And from Brian's chart, it also looks like oil gets thinner as it gets hot. :huh:

Okay this is VERY difficult to explain without going into fluid dynamics and all that mubo jumbo as it is very confusing. Took me lots of time to think about it in my head before it finally clicked when I first looked into it. Please bare with me on this.....

The way the bottles are numbered with there 5w-30's and 10w-30's which by the way is a very dated way to describe them is by lab tests done at different temperatures. For this purpose I just want to talk about your normal daily driven car, not your drag queens.

Okay so let me begin with the thickness levels. Automotive designers for the most part aim for an operating temperature of 212F (oil and water), with an oil thickness of 10. This is NOT the weight of the oil, IGNORE all that shit you read on the bottle for right now. 10 is the viscosity of the oil NOT weight, if our oil was 10 all day long regardless of temperature it would be having a ball. There would be almost no wear and tear on the motor and you wouldn't even need to warm it up, just start that baby up and step on the gas. Unfortunately that's not how it works.

I remember this example vividly but can't find a link I had GRRRrr. The example is you drive from work back home and your oil warms up to it's operating temp and all reaching the viscosity of 10. You come home you park and the oil cools and thickens over night. The next morning it's a viscosity of 150, super thick for start up temps. So now your thinking lets get the thinnest oil money can buy, well good luck finding something like that, remember as it warms up it get thinner. We don't want your oil turning into ignitable fumes now do we;)

I forgot to mention, your motors sees the most wear upon start up. The thinner it can be the better when cold. A 10W-30 would be about a 100 at 75F if I remember correctly and 10 at operating temp (212). We want to be as close as possible to 10 when cold but like I said this isn't a perfect world. Now a 0W-30 on the other hand would be about a 40 on cold start up and a 10 just like the 10W-30. Yeah the 40 isn't a 10 but it's damn sure closer than 100 which means less wear on start up, get it??????

I'm out of time, got class in a bit. This goes on much more deeper but I think if you put your mind to it you might be able to see it in your head. I'll finish this later tonight don't worry:)

[BRIAN]

I'm surprised nobody has responded, I'll let it sink in longer lol.

Here's the correct answer to what the "W" stands for. Straight from the ASE
http://www.focfloridaregion.com/edu/chapter7.htm

:thumbs_up:

oh oh that's the same article I have from Dr. Haas, sweet. I have it in a file. Read all of that and you'll understand much much more than what I have explained!!! I didn't realize it. My professor emailed me to search for SAE j300 and tada got more than I asked for.

[Damian]

I just dont like how there is no real standard. You should be able to go in to a store and get 5W30 and actually get 5W30, regardless of the brand. I use Mobil 1 5W30 in all my cars and they seems to be doing just fine. My Eclipse had 130k miles on it, warped the heads, and the cylinder walls still had the factory honing on them. So Im assuming the oil is doing its job.

[enkeivette]

I'm surprised nobody has responded, I'll let it sink in longer lol.

Here's the correct answer to what the "W" stands for. Straight from the ASE
http://www.focfloridaregion.com/edu/chapter7.htm

:thumbs_up:

oh oh that's the same article I have from Dr. Haas, sweet. I have it in a file. Read all of that and you'll understand much much more than what I have explained!!! I didn't realize it. My professor emailed me to search for SAE j300 and tada got more than I asked for.

I was waiting for you to finish, I still don't get it.

[Vettezuki]

I was waiting for you to finish, I still don't get it.

Multi-weight oils have different weight-characteristics according to temperature.

Repeat that like a mantra. It will come to my child.

Think of it as a two dimensional spectrum moving from "like the LOWER weight AT LOWER TEMP " to "like the HIGHER weight AT HIGHER temp"

[Vettezuki]

DISCLAIMER: This is my understanding. I hope it is basically correct. The following graph is not scientific; it is only intended to represent a relationship of parameters.

NOTE:
A 100 weight at 0C (32F) is going to be damn near a solid.
A 0 weight at 100C (212F) is going to be damn near like water.

THEREFORE:
- A Straight 10 weight oil at 100C is thinner than a straight 30 weight at 100C.
- Conversely, a straight 30 weight is thicker at 20C (68F) than a straight 10 weight at 20C.

The following graphs really need a 3rd dimension like a gradient, to help visualize thickness (what you perceive when you smear oil between your fingers). So use your imagination.

This is what a straight 10 would look like. Nice thinness for starting but too thin at operating temp.

http://motorgen.com/pic/data/500/Straight_10.jpg

A straight 30. Fine for operating temps, but pretty damn thick during startup, not offering a lot of protectino until the engine gets warm.

http://motorgen.com/pic/data/500/Straight_30.jpg

Behold the miracle of blended multi-weights and unwinding polymers. This graph is intended to show what a 10/30 oil might behave like on a typical day in CA where you start up at around 20C (68F) in the morning and bring up to something like a typical operating temp.

http://motorgen.com/pic/data/500/Weight_To_Temp.jpg

THIS IS THE POINT of a multi-grade oil. Relatively thinner at cooler (startup temps) and relatively thicker at operating temps. The real point is that something like a 10-30 offeres the protection of a 30 weight oil at operating temps, but offers lighter, easier starrting, quicker to lubricate, characteristics at startup temps.


BONUS:
Assuming a fairly static relationship, a 10 weight @ 20C will flow like a 90 weight @ 100C.

Simply stated, a multi-weight oil is just a way of optimizing lubricating characteristics according to two principle conditions; starting and running.

[enkeivette]

Ben, thanks for laying it out for me. I get what you're saying, just having a hard time buying it.

If weight is simply a measure of how long oil takes to drain through an orifice, the longer the thicker, than from my experience of doing hot and cold oil changes with 10w 30, it seems to me that this is false. Like I said, drains faster when hot. Using my oil drain plug as an orifice, it seems to me that hot 10w 30 is thinner than cold 10w 30. Which is obviously contrary to what you explained.

I could see making the case that the hot 10w 30, acts like a thick oil in some way even though it flows faster, but then how would you measure it? If weight is just a measure of flow vs. time... how do you measure how the oil 'acts?'

And really thanks again Ben and Brian for taking your time to lay it out.

[Vettezuki]

. . Using my oil drain plug as an orifice, it seems to me that hot 10w 30 is thinner than cold 10w 30. Which is obviously contrary to what you explained.


It is not contrary.

TEMPERATURE, TEMPERATURE, TEMPERATURE

Stare at the charts above. Note, weight, temp, thick and thin (and the fact I'm not completely representing the thick/thin part witha gradient or Z dimension). Remember I said a 10@20C while have a thickness like a 90@100C. Also keep in mind the charts are only intended to show relative thickness according to weight and temp.

The difficult part to understand is that the nature of a multi-weight oil is changing with temp. It's not thicker at higher temps, it behaves like a heavier oil at higher temps.

A hot 10 is thinner than a cold 10.
A hot 30 is thinner than a cold 30.

Depending on temps, a hot 30 is thinner than a cold 10. That's why as you stated, a hot 10/30 is thinner than a cold 10/30.

THE POINT of a multi-weight is that when hot it's acting more like a 30 at said higher temp, and when cold, more like a 10 would at said lower temp.

If it were a straight 10, it would be even thinner than 10/30 when hot. Maybe think of that way.



Or, another way, the point of a multi-weight:
A cold 10 is thinner than a cold 30. (GOOD)
A hot 30 is thicker than a hot 10. GOOD)

Best of both worlds.

(COLD) Like a 10 ------------------------------------------> Like a 30 (HOT)

The oil is NOT becoming thicker in absolute terms with an increase in temperature, it's just thicker than it would have been if it was a straight 10 for example.

In fact, in all cases it's going from relatively thicker to relatively thinner with temp in absolute terms. It's the spread that matters. A multi-weight allows the range to be constrained.

If it were a straight 10

(COLD) GOOD ----------------------------------------------> BAD - Too Thin (HOT)

If it were a straight 30

(COLD) BAD - Too Thick ------------------------------------------------> GOOD (HOT)

multi-weight 10/30

(COLD) GOOD -----------------------------------------------> GOOD (HOT)


Ok, I'm running out of ways to say the same thing. ;)

[BRIAN]

Vettezuki is doing a good job explaining it with the numbers on the bottle:). Those numbers are the ones that threw me off in the beginning so I try to avoid it all together, but I get your explanation perfectly.

Like I said it's very confusing, I asked the same questions and of course I too wasn't buying it. The problem is the numbers on the bottle throw you off, that whole 10W-30 junk. Your thinking, yeah because the 10W is smaller than 30 it should feel thinner to the touch when cold and thicker when hot. The bottles should be labeled with there thickness instead for example a 10W-30 I would label it more like 100-10, thickness of 100 when cold and 10 when hot or operating temp.

There would be chaos in the streets if that happened today, probably why they just keep on going with there weight system.

[BRUTAL64]

A very good way of explaining it Brian and Ben.:thumbs_up:

I learned this 30 years ago. When they first starting doing multi-weight oils, if you got it too hot it would turn to goo. So during the first few years, multi-weight oil had a bad rap.:rolleyes2:

[BRUTAL64]

You're not allowed to roll your eyes until after I fail to understand your explanation.

Ok, point taken.:thumbs_up:

[enkeivette]

The oil is NOT becoming thicker in absolute terms with an increase in temperature, it's just thicker than it would have been if it was a straight 10 for example.


Ooooooooooooooooooooooooooooooooooooooooooooooooo.

This sentence right here did it.

So a 10w 30 is as thick as a 30 WOULD BE at 100c and as thick as a 10 would be at 20c.

So 10w 30 does get thinner, just not as thin as straight 10.



After all of this, I think I might switch to 0w 30. Why not? Thinner at start up and the same at operating temp as a 10w 30.

[BRIAN]

I learned this 30 years ago.

I was -9 years old back then:p

[BRIAN]

After all of this, I think I might switch to 0w 30. Why not? Thinner at start up and the same at operating temp as a 10w 30.

Just wait until you walk to the register with your 5 quarts of 0W-30, the looks you'll probably get are priceless :eek:

YouTube - Castrol oil commercial (think with your dipstick)

That oil isn't a "real" synthetic by the way I just like the commercial :)

[enkeivette]

So in reality, nothing is getting thicker. 10w 30 is just 10 weight oil with more resistance to thinning as it gets hotter than straight 10.

[Vettezuki]

So in reality, nothing is getting thicker. 10w 30 is just 10 weight oil with more resistance to thinning as it gets hotter than straight 10.

That's one way to think about it :thumbs_up: The opposite way to think about it (and the original reason) is that it runs like a 30 weight but is thinner on start up.

The effect is achieved through a blend of oils and some pretty trick petro-chemistry.

[Vettezuki]

. . . . After all of this, I think I might switch to 0w 30. Why not? Thinner at start up and the same at operating temp as a 10w 30.

Some, notably GM, do not recommend using an oil with such a spread. It's mixed from considerably different bases and apparently is more prone to thermal breakdown.

[Vettezuki]

Fun fact.

Formula 1 cars use an engine oil that is a straight weight and very nearly the viscosity of water. It must be pre-heated and circulated through the engine (as well as the coolant) in a detailed procedure before firing the engine. Failure to do so correctly results in a about a $200k engine rebuild.

[BRIAN]

Some, notably GM, do not recommend using an oil with such a spread. It's mixed from considerably different bases and apparently is more prone to thermal breakdown.
The 0W-30???

[enkeivette]

If redline makes a 0w-30 I trust it. And my coolant never heats up more than 180, so I'm not so worried about thermal breakdown.

[Vettezuki]

The 0W-30???

I think they specifically refer to 10-40. :huh:

Anyway, I use 15-45.

[BRIAN]

http://www.redlineoil.com/products.aspx

I think they specifically refer to 10-40. :huh:
Good ol' GM
Anyway, I use 15-45.
How often do you change your oil?

[Vettezuki]

http://www.redlineoil.com/products.aspx


Good ol' GM

How often do you change your oil?

I only just made my 2nd change on Rotella. I'll probably change it something like not more than 3,000 miles or 3-6 months regardless. I'll have to get with the old-timer on all the other things he was saying about oil products and why he recommended Rotella as a very good off the shelf oil. I know he was big on acidity and, as I recall, something called TBN?

[BRIAN]

http://www.blackstone-labs.com/do-i-need-a-tbn.php

I've been recommended to Blackstone Laboratories multiple times, hear there the best in the biz. Might get my next oil change analyzed by them.

[Vettezuki]

http://www.blackstone-labs.com/do-i-need-a-tbn.php

I've been recommended to Blackstone Laboratories multiple times, hear there the best in the biz. Might get my next oil change analyzed by them.

I used them once for my old engine, just to see. They're great, very professional and give you detailed feedback. If you run your car HARD and analyzed every couple changes, you'd probably be able to detect negative trends long before catastrophic trouble.