Some basic but unanswerd questions about viscosity

[CyFi6]

Well, recently i have been trying to do all the reading i can on different oils, how they work and how they are rated, so excuse me for the number of questions i have been asking recently. There are a few things i still fail to understand about how viscosity is rated. I understand the whole cst viscosity rating works to an extent. I also understand (correct me if im wrong) that a 40w oil from two different manufacturers can have different cst ratings because of the different additives in the oil. What i don't understand is how they come about the 10w40 etc numbers. If cst has close to nothing to do with it, how do they come about labeling the bottle?


Also, why do they label the bottle as 10w40 etc, instead of using cst numbers? It seems most people don't understand the labeling on the bottle as it is, so wouldn't having the cst number be more beneficial and useful in general?

Another question. As i have read in the motor oil 101 guide, "a 0wXX is always better than a 10wXX. Always." Then why do they even sell 10w30, 10w40, 15w30 etc etc when the operating temperature viscosity is going to be the same always, but cold start is going to be thicker and thicker. Why do they continue to even make a 10w30/10w40 etc when there are 0w30/0w40 oils available? And why would anyone buy the 10w over the 0w? It just doesn't make sense to me.

I have seen on many bottles such as Mobil 1. They list the 10w30 full synthetic as a regular oil, but the 0w30 has all these special labels stating its "superior gas mileage" etc etc, when in actuality it is only going to save you gas mileage in the time it takes for the engine oil to reach operating temperature. Is it just a big marketing scheme?

Thanks for all the help, there is a lot of good info in this forum on lubricants and i have learned a lot already, but have a lot more to do!

 

[jdub]

Well, recently i have been trying to do all the reading i can on different oils, how they work and how they are rated, so excuse me for the number of questions i have been asking recently. There are a few things i still fail to understand about how viscosity is rated. I understand the whole cst viscosity rating works to an extent. I also understand (correct me if im wrong) that a 40w oil from two different manufacturers can have different cst ratings because of the different additives in the oil. What i don't understand is how they come about the 10w40 etc numbers. If cst has close to nothing to do with it, how do they come about labeling the bottle?

This is how the SAE and API classify oils:
http://www.supramania.com/forums/showthread.php?t=38811

basically the 1st number is the "cold" (40 deg C) viscosity and the 2nd number is the "hot" (100 deg C ops temp) viscosity.

Viscosity improvers (VI) are used to change the viscosity range of the base stock oil. VI's are long chain polymers that help hold the base oil in it's designed temp range to meet the above SAE classification...i.e a 0W-30.

Also, why do they label the bottle as 10w40 etc, instead of using cst numbers? It seems most people don't understand the labeling on the bottle as it is, so wouldn't having the cst number be more beneficial and useful in general?

This is one of those "we've always done it this way" things
I agree, cst viscosities for cold/hot would be far more useful. However, Ma and Pa Kettle would have no clue what they are looking at, much less what needs to go in the motor. The "10W-30" is easier to understand form this perspective.

Another question. As i have read in the motor oil 101 guide, "a 0wXX is always better than a 10wXX. Always." Then why do they even sell 10w30, 10w40, 15w30 etc etc when the operating temperature viscosity is going to be the same always, but cold start is going to be thicker and thicker. Why do they continue to even make a 10w30/10w40 etc when there are 0w30/0w40 oils available? And why would anyone buy the 10w over the 0w? It just doesn't make sense to me.

Marketing and demand. You've got folks out there that "always use" a 10W-40 because "that's what my Dad and granddad said was the best". They do what they do based on perception or "feel". The oil companies are simply meeting the demand

I have seen on many bottles such as Mobil 1. They list the 10w30 full synthetic as a regular oil, but the 0w30 has all these special labels stating its "superior gas mileage" etc etc, when in actuality it is only going to save you gas mileage in the time it takes for the engine oil to reach operating temperature. Is it just a big marketing scheme?

More marketing. If you read the thread I posted above, you can see what it takes to rate "Energy Conserving". Oil companies are just tacking additional BS in an attempt to make this 0W-30 "better" than that company's 0W-30,

BTW - a thinner oil at ops temp, assuming it gives you spec pressure, will save you gas. It's not just during engine warm-up.

Thanks for all the help, there is a lot of good info in this forum on lubricants and i have learned a lot already, but have a lot more to do!

Yep, it takes a while to filter out all the BS

 

[CyFi6]

Thank you for the very direct answers, this helps me a lot! One other question though, why aren't all manufacturers now calling for 0w oils in all their cars? I have noticed a lot of them are, and most have gone as low as a 5w, but why would they recommend 5w oils when 0w is so much better?

 

[jdub]

Personally, I think it's a perception thing. People see a "0W" and immediately think "that oil is thin as water", when reality is far different (GC 0W-30 is actually pretty thick for a 30 multigrade). Folks have a hard time believing a modern motor hits it's best efficiency on the 0W/5W-30 or 5W-20 oils. What matters is an oil's viscosity at ops temp...I have yet to see a 0W/5W-30 that did not meet the viscosity requirements for a 10W-30.

 

[suprarx7nut]

Great basic info. I myself, was also wondering about a few of the items stated above.

If jdub doesn't mind my poking, I've got one to add:

Why does Toyota have this figure in the owner's manual for the mkIII?

Why are 10W30, 15W40 and 20W50 on this chart? Why does the chart specifically recommend not using 5W30 above 50F?

Thanks!

Andy

 

[jdub]

You left something out...the verbiage above that chart:

Use engine oil of API grade SF, SF/CC, or SG. Determine the viscosity considering your climate. Recommended viscosity is as follows. Using multigrade and fuel-efficient engine oil is recommended.

Recommended viscosity (SAE):

Note...it says "recommended"...the chart says nothing about what is "not recommended".
Not too sure where you got "recommend not using 5W30 above 50F" from this chart because it does not say that at all. What it does say is a 5W-30 is recommended for OAT of 50 deg F and below and it recommends a 10W-30 for OAT of 0 deg F and above. If a modern API SM rated 0W or 5W-30 oil meets a 10W-30 viscosity spec at ops temp, are you saying you shouldn't use it? The chart says nothing about a 0W, 5W, or 10W-40...does that mean you can't use that grade oil in a 7M?

Note that it also recomends API grade SF, SF/CC, or SG....all of which are obsolete. Good luck finding the "recommended" oils.

See where this is going yet?

Think that motor oil technology (hydrocracking, base stocks, additives, etc.) just *might* have progressed a bit in the 20 years since that chart was produced? The 1st number is there to tell you what the oil's viscosity is cold...it has nothing to do (at all) with how the oil will behave at ops temp (100 deg C). ANY 30W multigrade is plenty thick enough for engine start; in fact, too thick to be run at that viscosity if it were retained all the way to ops temp. One more time...a 0W or 5W-30 oil is NEVER too thin to run in a 7M or JZ series engine for normal ops, at any OAT.

Of course, you don't have to listen to me at all...in fact you can disregard everything I say and use a 20W-50 if you wish...it is your motor. Who am I to tell you smart guys what to do

 

[orbis-gte]

i have broought my car not to long ago. and its a trubo. so im using mobile one 10-30 , and i think it works good , am i wrong?

 

[jdub]

Mobil 1 is not going to hurt your motor, but there's better oil for the $$$ available. Do some reading in this section and make up your own mind

Same concerning oil filters...there's a sticky on that one.

 

[suprarx7nut]

I think we have some confusion here. I realize that the chart is outdated and those classifications of oil are not available because they have been replaced by superior grades. No need to patronize me. Did I catch you on a bad day or something?

Note...it says "recommended"...the chart says nothing about what is "not recommended".
Not too sure where you got "recommend not using 5W30 above 50F" from this chart because it does not say that at all. What it does say is a 5W-30 is recommended for OAT of 50 deg F and below and it recommends a 10W-30 for OAT of 0 deg F and above.

What I was after is why the they ever stopped their recommendation of 5W30 at 50F? Looking at that chart, it is easy to see why people would think 5W30 could get too thin. I REALIZE 5W30 AND 0W30 ARE NEVER TOO THIN TO RUN IN OUR MOTORS. That's a dead horse that's well beaten with me.

If a modern API SM rated 0W or 5W-30 oil meets a 10W-30 viscosity spec at ops temp, are you saying you shouldn't use it? The chart says nothing about a 0W, 5W, or 10W-40...does that mean you can't use that grade oil in a 7M?

Absolutely not. I have no idea where you made that assumption. I, myself, use 5W30 oil in my 7M.

Note that it also recomends API grade SF, SF/CC, or SG....all of which are obsolete. Good luck finding the "recommended" oils.

See where this is going yet?

Think that motor oil technology (hydrocracking, base stocks, additives, etc.) just *might* have progressed a bit in the 20 years since that chart was produced? The 1st number is there to tell you what the oil's viscosity is cold...it has nothing to do (at all) with how the oil will behave at ops temp (100 deg C). ANY 30W multigrade is plenty thick enough for engine start; in fact, too thick to be run at that viscosity if it were retained all the way to ops temp. One more time...a 0W or 5W-30 oil is NEVER too thin to run in a 7M or JZ series engine for normal ops, at any OAT.

I know, I know, I know. Why do I feel like I'm being talked down to here? ...About things I already know, nonetheless.

Of course, you don't have to listen to me at all...in fact you can disregard everything I say and use a 20W-50 if you wish...it is your motor. Who am I to tell you smart guys what to do

I was asking to get your opinion because it is one that I respect and trust. I was NOT trying to argue that you are wrong and Toyota was right or some bullshit. :nono: Do you have me confused with somebody you have a beef with?

Again, my question was, and still remains: Do you know why the recommendation for 5W30 stops at 50F? Were oils back then, in fact, too thin at startup? :dunno: Am I just not understanding the chart?


Respectfully,

Andy

 

[jdub]

Andy - I apologize...I misunderstood what you were asking. No excuse, but I'm just getting over a bout of pneumonia...the drugs (especially the Hycodan) and being cooped up for the last 10 days is making me bitchy.

It wasn't that that a 5W-30 was too thin back in the late '80's...the SAE grade standards were basically the same. API has changed formulation/performance requirements, but not where viscosity is concerned.

The chart shows basically what I said...Toyota looks at it from a "recommended" view. If you plan on running the motor at OAT less than 50 deg F for extended periods, they want you to run a 5W-30. The chart is not displayed/explained very well...you can easily run a 5W-30 above 50 deg F OAT, but the other oil grades are available too. Keep in mind a 0W or 5W-30 oil was not a very common oil back then...look at it like Toyota was telling you it was OK to use. From that perspective, Toyota was way ahead of the game

 

[suprarx7nut]

Andy - I apologize...I misunderstood what you were asking. No excuse, but I'm just getting over a bout of pneumonia...the drugs (especially the Hycodan) and being cooped up for the last 10 days is making me bitchy.

It wasn't that that a 5W-30 was too thin back in the late '80's...the SAE grade standards were basically the same. API has changed formulation/performance requirements, but not where viscosity is concerned.

The chart shows basically what I said...Toyota looks at it from a "recommended" view. If you plan on running the motor at OAT less than 50 deg F for extended periods, they want you to run a 5W-30. The chart is not displayed/explained very well...you can easily run a 5W-30 above 50 deg F OAT, but the other oil grades are available too. Keep in mind a 0W or 5W-30 oil was not a very common oil back then...look at it like Toyota was telling you it was OK to use. From that perspective, Toyota was way ahead of the game

Gotcha. Didn't know the viscosity ratings haven't changed over the years. Makes sense though.

No hard feelings here, jdub. Thanks for the response.

 

[CyFi6]

I have another question I still struggle to find the answer to. I have read back through the Motor Oil 101 and the Motor oil basics thread, and I am still confused. Maybe someone can help me out.

I quote this from the Motor Oil Basics thread " Its viscosity rating is determined by the length of time it takes to flow out of the hole. If it flows quickly, it gets a low rating. If it flows slowly, it gets a high rating. SAE viscosity rating system applies to both conventional and synthetic oils."

I also quote this from the Motor Oil 101: "The problem is that the viscosity of oil varies with its temperature. A “30” weight oil has a viscosity of 3 at 302 F ( 150 C ) and thickens to 10 at 212 F ( 100 C ). It further thickens to a viscosity of 100 at 104 F ( 40 C ) and is too thick to measure at the freezing point of 32 F ( 0 C )."

Both these statements match and make sense for the ex. 10w30 number, saying that the thinner the oil is, the lower the second number on the bottle is. What i dont understand is how the ex. 10w30 first number is formed. If i follow the same rules as before, it would be as follows... The thinner the oil is, the lower the rating number on the bottle. Since the first number on the bottle indicates cold viscosity, and the second is warm viscosity, and 10 is a smaller number than 30, it must mean the oil is thinner and flows more quickly when cold than when warm. This of course doesnt make any sense, thus why I am confused with how the first number is come up with.

 

[Poodles]

First number is cold, the second is hot. The numbers are rated compared to a single weight oil. A 0w30 will flow like a 0 weight single weight when cold, but flow like a 30 weight while hot. This doesn't mean it thickens up as the numbers are compared to their respective single weights at the respective temperatures.

 

[CyFi6]

Ok cool didnt know that, that clears it up. So would a 10w30 with its additives work as a strait 30wt without additives when warm? so basically when warm, a 10w30 with additives would be the same viscosity as a strait 30wt with no additives?

 

[jetjock]

The "w" mean winter, not weight...

 

[CyFi6]

The "w" mean winter, not weight...

...I understand that. The motor oil guide refers to it as 30 "weight".