Topic: Oil viscosity choices?

[HondaMan]

Here are two viscosity questions to ponder.  First consider that engine oils at the thin end of the range might be 0W20 and at the thick end 20W50.

First question.  If your bulk oil temperature in the sump is 110 C, then maybe in bearings and the ring zone the oil might be 130 C or so.  Let's call this the oil's temperature when it is "on duty" and working to lube things.  Then what is the difference in viscosity between 0W20 and 20W50 at 130 C?

Second question.  If viscosity is the oil's physical property that separates the bearing surfaces, then how does the oil film thickness change with changing viscosity.  For example, does doubling the viscosity double the oil film thickness?  Or is it some other relationship like squared or square root, or cubed or cube root?

When we answer these questions, we will answer this thread.

One of the accurate ways to 'view' the viscosity numbers (per the Conoco Oil training I had in the 1980s, from their engineers) is to look at the "base number" of the oil first. This is the oil on which the product is "built". For example, 20w50 oil is a 20w oil that has long-chain molecules (either polymers or synthetic versions or constructions) added that try to hold the oil body at 20w thickness when operating at 210 degrees F. That's the measurement criteria in use for the "SF" rating for cars, which was current at that time. Conversely, a 0w20 oil maintains a performance viscosity of 0 weight (i.e., almost water) at 210 degrees F.

The upper number comprises the body weight of the oil at 0 degrees F. So, a 10w40 oil acts like 40w at 0 degrees F and 10w at 210 degrees F.

While it is a little more complicated than this, due to additives, modifiers, and the type of oil material (synthetic, mineral, or petroleum, in declining protective levels) that confuse it a little, this is the basic premise of multi-weight oils.

A straight-weight oil is (was) measured as the viscosity it will hold at 210 degrees F, using these rules. Keep in mind: the old bike manuals went by these rules, so it is often wise to "think old school" when doing this...

Starting in the 1990s, new rules, using meshes, sieves, metering holes, etc. to check or rate the viscosity numbers arrived, and by rating "SJ" it suffered the loss of zinc protectants. Overall, this means it does not protect as well for a given weight as it once did, further confusing these issues today. New metal-to-metal contact protection ratings are being created, even as I type this, using the lengths of the molecules of the oils as the yardstick, so I'm sure it will get even more obscure, soon.

[TwoTired]

The upper number comprises the body weight of the oil at 0 degrees F. So, a 10w40 oil acts like 40w at 0 degrees F and 10w at 210 degrees F.

All my training says the rating operates exactly opposite of this.

IE.  10W40  behaves like 10 wt (the base stock) when cold and 40 weight when hot (due to the long chain polymers shrinking/coiling up with heat) in the oil additive package.

In fact, you wouldn't want sluggish poor flowing super thick oil when the engine is cold.  You want it thin and circulating well at low temp.   The base stock film strength degrades with temperature which is why there are the long chain molecules to reinforce the film strength when the oil is elevated in temperature and keep it from exiting the bearing journals faster than it can flow into them.

Multi-vis oils were an improvement over the straight weight oil once commonly used, which were either too thick to circulate when cold or too thin the yield the proper film strength when hot.


One of the reasons why oil changes are necessary is that the multi-vis long chain molecules get chopped up (shorter) with use, which makes the oil revert to it's base stock viscosity at all temps, leading to more engine wear while the engine is at operating temp.

[cakey]

This is getting very deep. I think you blokes have forgotten more than I know. Great read and appreciate the input about oils, way more info than I expected.

By the way Hondaman just started reading your book today. It's a great read. By page 13 it had paid for itself already. I got the rings in the cylinder block (none broken rings this time) and have it sitting just above the cases whilst I get everything prepped overnight to put the head on tomorrow. I want to put the little bit of case bond on the gasket in the areas you mentioned so want to be ready.

Good stuff and hope you never threw out those trackies in the first picture they are collectible classics now days.

[KJ790]

The upper number comprises the body weight of the oil at 0 degrees F. So, a 10w40 oil acts like 40w at 0 degrees F and 10w at 210 degrees F.

All my training says the rating operates exactly opposite of this.

IE.  10W40  behaves like 10 wt (the base stock) when cold and 40 weight when hot (due to the long chain polymers shrinking/coiling up with heat) in the oil additive package.

In fact, you wouldn't want sluggish poor flowing super thick oil when the engine is cold.  You want it thin and circulating well at low temp.   The base stock film strength degrades with temperature which is why there are the long chain molecules to reinforce the film strength when the oil is elevated in temperature and keep it from exiting the bearing journals faster than it can flow into them.

Multi-vis oils were an improvement over the straight weight oil once commonly used, which were either too thick to circulate when cold or too thin the yield the proper film strength when hot.


One of the reasons why oil changes are necessary is that the multi-vis long chain molecules get chopped up (shorter) with use, which makes the oil revert to it's base stock viscosity at all temps, leading to more engine wear while the engine is at operating temp.

This is correct, the first number for a multi-grade oil is the cold viscosity, the second is the hot viscosity.

[lrutt]

I used to be a 20w50 regular dino MC oil guy in all my bikes. I've since converted to Shell Rotella T6 5W40 syhtetic in everything. Honestly can't tell a difference, temps consistent with what they used to be on the bikes with temp guagues, pressures consistent on bikes with pressure gauges. Shifting and clutch action the same.

T6 is MA (bike) rated and reasonably priced and very available.

And this is used in every bike in my sig line.

[TwoTired]

I had his memory rattling around upstairs, of people changing oil with the seasons during the period when I grew up in Illinois.  Spring and Fall were when this was routinely performed in a time period where multi vis oil wasn't available for the average auto owner.
  I happen to have a Motor's manual (book actually) that covers American auto years 1940 to 1954.  Sure enough, there are no multi-vis oils listed.  All straight weights, to be used according to the temperatures the machine was to be operated within.

Chrysler, for example used 30W when above 32F, 20W when above 10F, and 10W when above -10F.   The other brands, such as GM, used 20W above 10F and 10W above -10F.  I assume engine preheat was required in starting temps below -10F.  I recall seeing a car from North Dakota, with an engine block AND battery heaters installed.  And, I recall later fitting an engine block heater to one of my cars (61 Ford), to help cold starting. 
Dad used to put a 100W light bulb on the block and a blanket over the motor for those subfreezing nights.  One morning he discovered his Light green 53 straight eight Pontiac burned up in the night.  A total loss and really stinky even though the flames never reached the gas tank.  At age 8 or 9, I confirmed my parents were fallible, even if all powerful. 

Don't think it was until the late 50s and 60s that multi-grade oil was the new sensation in the automotive industry.  As I recall, 10W30 was the first to become widespread.  Note how it aligns with Chrysler's engine requirements, and allows oil changes to be mileage based instead of seasonal, an owner convenience.  I believe GM followed suit and specified 10W30 for engines in the 60's, as I did all the oil changes for the family cars until I left for Navy service.

I checked my 1972 CB500 owners manual (the earliest Honda owner's manual I have.  It states 10W-40 for all temperatures and 20W-50 for temps above 59F (15C).  It also specifies straight weight oil viscosities for temp. break points of above 59F, 59-32F, and below 32F, as 30, 20 and 10 weight viscosities.

I wonder how many here start their bikes in temps below 59F, yet insist on 20W50 oil?

[AJK]

Yeah it can be a mindbender, depending on how you look at it. My understanding was more in line with TwoTired's, but Hondamans also makes sense if you look at it from the other angle.

I always thought the base stock didn't change, but rather the depletion of the additives causing the loss of viscosity at higher temps with aged/used oil.
  I.e. The oil molecule itself never breaks down & therefore gets re-used over and over in the recycling process. Its the additives that need replenishing.

Regarding the polymers, I also thought that the polymers are coiled up when the oil is cold (like shrunk testicles in the snow). This leads to the base stock viscosity taking precedence in operation. When the oil heats up, the polymers uncoil, stretch out their arms and become long which creates the added thickness to the oil when hot so it doesn't overly thin-out.

In other words, if we look at the graph on this pdf

http://www.penriteoil.com.au/tech_pdfs/204%20-%20Technical%20Bulletin%20-%20What%20is%20the%20Penrite%20Extra%20Ten.pdf

we can see the oil thins out linearly with temperature. So the gradient of the graph will have a certain slope for lets say "newish" oil. As the oil gets used up (or rather the additives get used up since the oil molecule never breaks down), the slope gets even slopier as the oil becomes old/used.
  This is a bit like saying that you might start out with 10-50 new out of the bottle, but ride it for 6 months & it behaves more like 10-30.

PS: These fact sheets are interesting to read (a bunch of pdf's excellently written)
http://www.penriteoil.com.au/faq.php

If you go to the 'technical' tab at the top of the screen on their site, you can go through the fact sheets and other goodies. These guys really know their stuff & their articles are great.

[HondaMan]

Sorry guys, but here it is, from the engineering organizations who make these oils:

What Do the Numbers Mean?

Most people believe that a 5w30 oil is good for cold weather use because it is a “5 weight” oil in cold temperatures and a “30 weight” oil at high temperatures. On the surface this might seem to make a certain amount of sense. Naturally, a “5 weight” oil would flow better than a “30 weight” oil. This would make it ideal for cold temperature operation.

Nevertheless, this is a profound misunderstanding of what the labeling means. The two numbers really have little to do with each other. The final number is based upon the kinematic viscosity of the oil at 100 degrees C, as we discussed for monograde oils.

So, if a multi-grade oil, when heated to 100 degrees C, falls within a certain kinematic viscosity range it is classified as a certain SAE grade (the last number – like the “30″ in 5w30). In other words, the kinematic viscosity of a 5w30 multi-viscosity oil falls within the same range at 100 degrees C as a monograde SAE 30 weight oil does.
5w is NOT 5 “weight”

Read more: http://themotoroilevaluator.com/members-blog/understanding-multi-viscosity-oils/#ixzz2nDUYwGkM

http://themotoroilevaluator.com/members-blog/understanding-multi-viscosity-oils/#axzz2nDUJxQJZ

[AJK]

Nevertheless, this is a profound misunderstanding of what the labeling means. The two numbers really have little to do with each other. The final number is based upon the kinematic viscosity of the oil at 100 degrees C, as we discussed for monograde oils.

Ok, so it looks like its the last number that dictates the base viscosity & I think you were implying this in your earlier thread.

I've also had previous conversations with others quite some time ago, in that the two numbers in the oil rating are actaully different scales. I.e.  A cold scale and a hot scale. So they should be treated separate and not compared to each other numerically. In a way, this supports what your saying.

[TwoTired]

It seems the linked sites are there to sell you a book or get advertizing fee/credit.

TheMotorOilEvaluator.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com.

So, its a word game, and you should buy their book to unravel the mysteries in their site text.    Feh

Summary:  a 10W40 oil behaves in the engine as 40 viscosity when hot and a 10 viscosity when cold.

The internet has other sites, too.
http://auto.howstuffworks.com/fuel-efficiency/fuel-consumption/question164.htm

"The viscosity grade (for example, 5W-30) tells you the oil's thickness, or viscosity. A thin oil has a lower number and flows more easily, while thick oils have a higher number and are more resistant to flow. Water has a very low viscosity -- it is thin and flows easily. Honey has a very high viscosity -- it is thick and gooey.


Measuring Motor Oil Viscosity

The standard unit used to measure viscosity is the centistoke (cSt). According to the Automotive and Industrial Lubricants Glossary of Terms:

    Viscosity is ordinarily expressed in terms of the time required for a st­andard quantity of the fluid at a certain temperature to flow through a standard orifice. The higher the value, the more viscous the fluid. Since viscosity varies inversely with temperature, its value is meaningless unless accompanied by the temperature at which it is determined. With petroleum oils, viscosity is now commonly reported in centistokes (cSt), measured at either 40°C or 100 °C (ASTM Method D445 - Kinematic Viscosity).

­The centistoke rating is converted into the SAE weight designation using a chart like the one shown on the Superior Lubricants Web site.

Multi-weight oils (such as 10W-30) are a new invention made possible by adding polymers to oil. The polymers allow the oil to have different weights at different temperatures. The first number indicates the viscosity of the oil at a cold temperature, while the second number indicates the viscosity at operating temperature. This page from the Sci.Electronics.Repair FAQ offers the following very interesting description of how the polymers work:

    At cold temperatures, the polymers are coiled up and allow the oil to flow as their low numbers indicate. As the oil warms up, the polymers begin to unwind into long chains that prevent the oil from thinning as much as it normally would. The result is that at 100 degrees C, the oil has thinned only as much as the higher viscosity number indicates. Another way of looking at multi-vis oils is to think of a 20W-50 as a 20 weight oil that will not thin more than a 50 weight would when hot. "

[HondaMan]

Nevertheless, this is a profound misunderstanding of what the labeling means. The two numbers really have little to do with each other. The final number is based upon the kinematic viscosity of the oil at 100 degrees C, as we discussed for monograde oils.

Ok, so it looks like its the last number that dictates the base viscosity & I think you were implying this in your earlier thread.

I've also had previous conversations with others quite some time ago, in that the two numbers in the oil rating are actaully different scales. I.e.  A cold scale and a hot scale. So they should be treated separate and not compared to each other numerically. In a way, this supports what your saying.

You've hit the nail right on the head, sir: the first number is rated differently from the second one.

[KJ790]

Like I said before, the first number is the SAE grade (viscosity) when cold, the second is the SAE grade (viscosity) when hot. Conventional multi-grade oils are made with a base oil of the of the lower SAE grade (i.e. a 10w40 oil is made with a 10 grade base oil). Polymers are then added to the oil that increase the hot viscosity so that it will act like a higher grade oil at higher temperatures. These polymers can get broken down over time, especially when exposed to high temperatures and high shear loads. This is why low quality oil will break down. I have sent used samples of boutique "motorcycle specific" oils to blackstone labs only to find that they had broken down from a 10w40 to a 10w20 after only 2 hours of runtime in a bike. From the used samples I have had analyzed out of my personal race bikes and street bikes, I have found that Shell Rotella T and Shell Rotella T6 synthetic both hold up very well in motorcycles, better than some "motorcycle specific" oils that cost 3-4 times as much.

[lrutt]

Like I said before, the first number is the SAE grade (viscosity) when cold, the second is the SAE grade (viscosity) when hot. Conventional multi-grade oils are made with a base oil of the of the lower SAE grade (i.e. a 10w40 oil is made with a 10 grade base oil). Polymers are then added to the oil that increase the hot viscosity so that it will act like a higher grade oil at higher temperatures. These polymers can get broken down over time, especially when exposed to high temperatures and high shear loads. This is why low quality oil will break down. I have sent used samples of boutique "motorcycle specific" oils to blackstone labs only to find that they had broken down from a 10w40 to a 10w20 after only 2 hours of runtime in a bike. From the used samples I have had analyzed out of my personal race bikes and street bikes, I have found that Shell Rotella T and Shell Rotella T6 synthetic both hold up very well in motorcycles, better than some "motorcycle specific" oils that cost 3-4 times as much.

    that is what my research found as well. If Rotella can withstand the extended pounding in big diesels it seems to have superior performance in motorcycles, thus the MA rating.

IMO, the other thing to remember that even the cheapest oil these days is superior to anything that was produced when these bikes were manufactured in the 70's.

[HondaMan]

IMO, the other thing to remember that even the cheapest oil these days is superior to anything that was produced when these bikes were manufactured in the 70's.

Well, that may have been true, until about 2002 when the best oils we ever saw for these bikes were outlawed in the US, by our own EPA. Since then, those of us who have had these bikes for a long, long time can tell unequivocally that today's oils do not work as well: we now have shifting issues, clutch issues, hot-engine issues, and top-end valve guide wear issues that never existed until then.

Two things happened in 2002: first, the EPA outlawed zinc as a major component of the lubrication (and for nefarious reasons I have mentioned elsewhere). I have written some articles about it, as have many others: this is a serious problem, and those who were hit hardest by it were the truckers. It decimated diesel engines and it took (literally) an act of Congress to allow zinc to remain in at least "diesel class" oils. That's why you will often see me recommending those oils for these bikes, if you can find some with low detergents. The second thing was: Congress pushed [everyone] for longer oil change intervals, bribed to by the Greenies, to "reduce waste oil pollution", which is one of the largest lies from that group, yet. Their intent was to hurt 'big oil' [whatever that means] by reducing their sales of motor oils by convincing the public, both though laws being passed and fraudulent advertising in many places, that "used" oil from cars is very bad for the environment and can make you sick. They even went so far, starting in the late 1980s, as to get a bunch of doctors to say that handling used oils will give you cancer: this was completely debunked by several independent studies since then, none of which were funded by 'big oil'. Even the liberal National Geographic debunked this one.

The result: today you are being told that your engine can go 7,500 miles without an oil change on conventional oils, and up to 25,000 miles on fully synthetic oils. Like KJ790, I have participated in many oil analyses of used oils, sampling them at various time/mileage intervals, to see how well they are doing: in our SOHC4 bikes, I can tell you this much for sure:  Honda wasn't kidding with their oil change intervals, and they are MAXIMUMS, even with "modern" oils. Some folks are 'amazed' that I got 138k miles from my 750 before this current rebuild (and Ofreen even more on his), but I have stayed with the 1000 mile oil change for all but 8 of the changes for all 40+ years. Even now, my engine had so little wear inside that I only bored it because a chunk of carbon had scratched the #1 cylinder wall (and I'm a bit of a perfectionist about such things...).

Synthetic oils are another story, the change-interval chapters of which have not been written for these bikes, but our experiences in these forums do show that they are mighty hard to keep inside the engines.

[AJK]

Thanks Hondaman, thats a pretty good writeup and you have the history data to back it up.

I've come to the conclusion that anything mineral or semi-synth JASO MA rated should be good for our machines, assuming the weight is chosen accordingly for the given temperature environment.
  I'm not 100% sure but i've got a feeling that JASO MA rating might have to do with full(er) zinc levels in the oil. I'll have to look up where JASO MA differs to the other ratings.

If we stick to 1000 mile changes, these motors will probably outlive us. Still the cheapest insurance route to take, so change frequently.

I've just run my motor in (done about 1200 miles so far after doing just a top end refresh with new rings only - no bearings as the bottom end was fine). The bike runs great and doesn't smoke. Whats your thoughts on changing oil filters under 'normal' (run-in) operation? My thoughts are that they could conservatively be changed every 2nd oil change. How often do you change your filter?

During run-in, I changed the filters a few times. The first time, heaps of metal shavings (after 15 miles or so), the 2nd a lot less but still visible. Now its almost coming out with nothing in it. The metal fragments tend to collect in the V-Grooves of the filter as you would expect.

So whats your thoughts on filter changes? On every 2nd oil change or on every oil change? I ask this because i don't see the filter getting that dirty once the motor is run in. The filter, apart from looking wet has almost no debris in it so i'm thinking i'd be changing it for nothing really.

PS2: Has anyone thought of installing a big heatsink on the oil tank for giggles? Not sure if there is room, but it might help draw some excess heat out of the system at speed (without having to install an oil cooler).

[Update] - I just checked the manual re:filter change. Honda recommends every 3000 mile, so its on every 2nd oil change.

[HondaMan]

Thanks Hondaman, thats a pretty good writeup and you have the history data to back it up.

I've come to the conclusion that anything mineral or semi-synth JASO MA rated should be good for our machines, assuming the weight is chosen accordingly for the given temperature environment.
  I'm not 100% sure but i've got a feeling that JASO MA rating might have to do with full(er) zinc levels in the oil. I'll have to look up where JASO MA differs to the other ratings.

If we stick to 1000 mile changes, these motors will probably outlive us. Still the cheapest insurance route to take, so change frequently.

I've just run my motor in (done about 1200 miles so far after doing just a top end refresh with new rings only - no bearings as the bottom end was fine). The bike runs great and doesn't smoke. Whats your thoughts on changing oil filters under 'normal' (run-in) operation? My thoughts are that they could conservatively be changed every 2nd oil change. How often do you change your filter?

During run-in, I changed the filters a few times. The first time, heaps of metal shavings (after 15 miles or so), the 2nd a lot less but still visible. Now its almost coming out with nothing in it. The metal fragments tend to collect in the V-Grooves of the filter as you would expect.

So whats your thoughts on filter changes? On every 2nd oil change or on every oil change? I ask this because i don't see the filter getting that dirty once the motor is run in. The filter, apart from looking wet has almost no debris in it so i'm thinking i'd be changing it for nothing really.

PS2: Has anyone thought of installing a big heatsink on the oil tank for giggles? Not sure if there is room, but it might help draw some excess heat out of the system at speed (without having to install an oil cooler).

[Update] - I just checked the manual re:filter change. Honda recommends every 3000 mile, so its on every 2nd oil change.

Yep, you'll got it: every 2nd oil change was the Honda method. On the first K0 bikes' setup sheets we first saw, they had a 50-mile oil-and-filter change scheduled, which quickly (by summer, 1969) became 150 miles. The Honda dealer was supposed to pay for this, and the shop where I worked refused, so it never was done. Instead, they had the customer come in at 500 miles. Soon after (1970, Spring or so) the Honda setup sheets showed 500 miles. By the K2, it was showing 1000 miles.

The K0 sometimes would show shiny things in the filters. The later bikes, not so much. After a rebuild, I often find shiny baubles after my first 15-minute run-in, and replace the oil and filter, like the old K0 rules. After that, it is every 800 miles until I reach about 2400 or so, then I switch to 1000 miles and filters every other time.

But, I have OCD about this...

I contact those great Aussies about their Penrite oil, and they are very proud to note their motorcycle-type oils have lots of zinc, on purpose. So, I'm going to try a case, as soon as I can contact their West Coast vendors. Hmm...maybe I'll become an importer?

Film at 11 PM...

[AJK]

I've found some interesting oil related links below that are great time killers if you are so inclined.

http://www.cbxclub.com/timoil.html

http://www.vfrworld.com/tex_vfr/tech/oil.htm

also, This link is interesting in that there are graphs and comparisons against different brands and their constituents.


part 1
http://www.sportrider.com/tech/146_0308_oil/

part 2
http://www.sportrider.com/tech/146_0310_oil/



PS: Hondaman, good luck with the Penrite. Please let us know your experience with it in due time.

[dave500]

i made enough pop corn for everyone.

[cb650]

I wish rotella made a 20/50.

[dave500]

too thick man,you live on the sun?

[lrutt]

dont use synthetic or semi synthetic diesel oils,the clutch will slip,most of these are for modern diesels which these days have particle filters and a sort of lean burn ecu controlled fuel system and mostly have the wrong slippery stuff in them.

Not necessarily true. Shell Rotella T6 here in the US is MA rated specifically for motorcycles as well as diesels. It's a synthetic 5w40 which works fine for the type of riding I do.

[dave500]

thats why i used the words most and mostly.

[nccb]

have ye people not learned. Do NOT get involved with oil threads

[AJK]

Your not wrong. Its definitely a *slippery* topic. 

[dave500]

nyuck nyuck nyuck!this is the last one for me,unless,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,?