What Does that Oil Can Labelled Grade Really Mean?

[AEHaas]

Originally Posted By: CATERHAM

Originally Posted By: virginoil

Its good to see Redline make the 10w60 grade for BMW, I wish they would just get it approved.

Red Line is a boutique formulator that chooses not to submit their oils to anyone for approval. As A_Harman pointed out, RL recommends their VII free HTHSV 3.8cP 5W-30 in place of the TWS 10W-60 for M series BMWs and not their own 10W-60. RL made the grade available because it's "popular" but it's not actually recommended by them. And with a HTHSV of 6.7cP it is indeed a extremely heavy oil; much more so than the 5.4cP TWS 10W-60, an oil that is know to shear as much as 25% in service. Even RL's 5W-50 (HTHSV 5.9cP) is still way heavier than TWS 10W-60. If I had an M series BMW for which TWS 10W-60 was spec'd that's the only 10W-60 I would consider using. It's the oil that's important not the grade on the bottle. In reality this oil has the viscosity closer to that of a heavy 40wt oil in service. Way too much is made of the grade on the bottle.

I quoted this from another thread. It brings to mind the most common problem on oil forums - the label on the can (as I see it). All day long people say to use the oil grade recommend in the owners manual. They answer the question as to the problems associated with using a grade below what is the OEM recommendation. Never do these people take into account the actual, real viscosity of the oil when poured out of the can nor the viscosity after 500-1,000 miles of use. Many oils thin considerably in this period. Then there is the engine related changes that occur as thinning from fuel dilution and shear forces. Let’s next look at HTHS viscosity and the effects of shear and of fuel dilution. In the end the viscosity is most often radically different than what is advertised on that oil can label. So why do people most often refer to the label when only an oil analysis can tell what oil viscosity is being run in that engine? My opinion is that most advice given here is misguided when trying to be specific with regards to viscosity. They assume the viscosity is stable. It is dependent on so many things. Many (some) oils resist viscosity changes by fuel dilution. Better VII compounds resist early breakdown and thinning. Other oils maintain original viscosities and may be higher or lower from the onset. One needs to be very, very specific about recommendations. Is the viscosity actually that important? Should we be concerned about other criteria? There are so many within the realm of motor oil. This is one of the reasons motor oil piques my interest. My original premise is that you need to base viscosity recommendations on many of these changing parameters is still true. Oil is dynamic. It is not possible to make blanket statements. Generally speaking, I look for viscosity stability rather than initial labelled viscosity grade. I prefer oil that does not thicken much on engine shut down. One of my greatest fears is damage from cavitation related to too much RPM for the viscosity during the early 20 or 30 minute start up period even here in Florida. aehaas PS- ‘Quality flack jacket donned, actually never doffed on this site.

 

[CATERHAM]

No disagreement from me. And in the same thread the discussion continued: http://www.bobistheoilguy.com/forums/ubb...298#Post2481298 The grade on the bottle is the starting point, but if you really want to compare the initial expected viscosities of a bottle of oil and how it will behave in your engine, the viscosity spec's to compare are HTHS and the viscosity index. Oils with the same HTHSV and VI will have identical operational viscosities; i.e., the same oil pressure at all oil temp's generally above 0C. That's at least initially. An oil's propensity to shear once it is in service is another matter.

 

[JHZR2]

Originally Posted By: AEHaas

My original premise is that you need to base viscosity recommendations on many of these changing parameters is still true. Oil is dynamic. It is not possible to make blanket statements. Generally speaking, I look for viscosity stability rather than initial labelled viscosity grade. I prefer oil that does not thicken much on engine shut down. One of my greatest fears is damage from cavitation related to too much RPM for the viscosity during the early 20 or 30 minute start up period even here in Florida.

Do we have established, peer-reviewed literature results that show that oil cavitation is indeed an issue, particularly at relatively high ambient temperatures such as in florida? Of course we have theories and analysis like this: http://keilab.mech.okayama-u.ac.jp/research/cavitation/cavitatione.html But in practice is it a condition that occurs at the Reynolds number occurring within the system? Sure, we get people who claim speeds like 5500 RPM and above will show cavitation: http://www.enginebuildermag.com/Article/59172/oil_pump_technology.aspx But frankly, it is silly to run hard until the oil is up to temperature anyway, and given all the 200k+ honda engines which need to rev fast when cold to make power, even if we are trying to split hairs and optimize our lubrication, I wonder how much of an issue it is. There is a reason why we have EP and AW adds, and why we see a minima in wear on the Stribeck curve when we hit the point between mixed film and hydrodynamic lubrication. Cavitation may not necessarily be a continuous occurrence either, as the fluid velocity transitions into steady flow, any shear-induced thinning occurs, there is local heating, viscosity decreases, etc. I do not believe that this is an issue to anyone but the user of the most exotic or race-type engine, and even then it may not be a practical issue for all intents and purposes. Now, I agree that oil is dynamic, especially over the OCI and conditions incurred. That's for sure. But IMO that has also been part of the consideration set in engineering and specifying a lubricant to do a job. One of the comments when people were transitioning from 5w-30 to 5w-20 oils was that the 30wt oils often sheared down into a heavy 20, so people HAVE been running lighter oils for a long time and not known it. The intent of that comment was to show that if the 5w-20 oils coming on market are shear-stable, then it is no different than what ran in most sumps for the last 1500+ miles anyway for years and years past. UOA is no newfangled technique. Engine manufacturers and lubrication engineers know what an oil will look like after a relevant amount of shearing, heating, oxidation, etc. These are all knobs which can be turned (look at older versions of M1 0w-40 which competed shearing with oxidation to maintain a 40wt A3 oil) as part of the lube design. The engine builders know what they need to know - Viscosity, rotational speed and load. From Noria: This stuff is easily calculated for designs and across the lifecycle of the engine and lubricant. There is sufficient variability in lube options that the "right one" can be specified or a specification can be written to make it work. Example: is 10w-60 REALLY necessary for an M engine? Maybe really a 50wt is necessary, but given the characteristics of service interval and available lubricants, the 10w-60 was selected to provide the maximum "time at rated condition" (which is what engineering stuff is really about) to provide "design life at rated condition". That is the end game and goal. To do that, as cheaply as possible, with just enough overdesign to ensure optimal MTBF/MTBO and customer satisfaction without costing too much in NRE, parts, labor, etc. So while I concur with your claim, I think that for the most part, statistically significant information has suitably indicated a non-issue using the specified lube for the specified interval in ones' engine. That doesnt mean to pack up shop and go home, but it does generally mean that using the recommendation is a fair approach that has been successful, and optimization, if any, is generally done more for sport/hobby than to see practical longevity improvements.

 

[Doug Hillary]

Hi, AEHaas - You said this: "All day long people say to use the oil grade recommend in the owners manual." This is very sound advice for Mr Average Motorist - and perhaps "According to the API/ACEA specification or/as stated by the Engine Manufacturer" should be added Mr Average Motorist buys millions of cars - about 18 million in China alone last year JHZR2 - Great, accurate and meaningful stuff again!!!

 

[hooligan24]

but, dont most manufacturers state to use an oil that meets a certain spec, which in turn would meet a minimum ht/hs? If most people would follow owners manuals, they would have a long happy life with their engines.

 

[jaj]

Originally Posted By: JHZR2

...Example: is 10w-60 REALLY necessary for an M engine? Maybe really a 50wt is necessary, but given the characteristics of service interval and available lubricants, the 10w-60 was selected to provide the maximum "time at rated condition" ...

I think that CATERHAM put it rather eloquently when he said (in another thread today) that BMW chose Castrol TWS Motorsport oil. They didn't choose a 10w-60 oil, except to the extent that TWS happens to be branded 10w-60. Regardless of its viscosity and viscosity dynamics, it's the total product that works, not the viscosity.

 

[JHZR2]

Originally Posted By: jaj

Originally Posted By: JHZR2

...Example: is 10w-60 REALLY necessary for an M engine? Maybe really a 50wt is necessary, but given the characteristics of service interval and available lubricants, the 10w-60 was selected to provide the maximum "time at rated condition" ...

I think that CATERHAM put it rather eloquently when he said (in another thread today) that BMW chose Castrol TWS Motorsport oil. They didn't choose a 10w-60 oil, except to the extent that TWS happens to be branded 10w-60. Regardless of its viscosity and viscosity dynamics, it's the total product that works, not the viscosity.

Not sure if I agree with that. BMW probably did some analysis, maybe even FEM, and found that a certain viscosity (not necessarily 60) was necessary. They then considered the pump volume capability, flow characteristics across the temperature range, engineering overdesign, etc., and found a true target viscosity. From there, they selected an oil that met their needs (from their marketing partner, of course). This drove the 10w-60. I wonder if syntec 5w-50 was still on the shelves in NA, if that might have been used?

 

[jaj]

Originally Posted By: JHZR2

Not sure if I agree with that. BMW probably did some analysis, maybe even FEM, and found that a certain viscosity (not necessarily 60) was necessary. They then considered the pump volume capability, flow characteristics across the temperature range, engineering overdesign, etc., and found a true target viscosity. From there, they selected an oil that met their needs (from their marketing partner, of course). This drove the 10w-60. I wonder if syntec 5w-50 was still on the shelves in NA, if that might have been used?

We're probably in violent agreement on this, just saying it a different way. The history goes like this: BMW and Castrol have collaborated on the TWS formulation since the somewhere in the 1990's when the product was actually called Castrol Racing Syntec RS 10w-60. I have one of those old bottles in my garage. It was a Grp V based racing oil that competed with Motul and Elf as an exotic racing oil. I'm not sure what BMW actually used it for in those days - it wasn't in any production cars. I suspect it was BMW Motorsports that was the actual customer for their racing programs. When BP rationalized the Castrol product line, they reformulated RS with Grp IV base stock for the retail channel, so BMW licensed the old ester formula and kept it in production as TWS 10w-60. Along the way, BMW M division started using RS/TWS in their engines. The first one was the S62 V8 in the M5, followed by the S54 engine in the E46 M3. Then they adopted their "high revving naturally aspirated" strategy for the M cars, and TWS became the flagship oil for M engines. So, that straight line through the history of the product prompts me to contend that when the later clean-sheet engine designs (the S85 V10 and the S65 V8) were started, it was a baseline design assumption that TWS would be the lubricant that designers worked around. The oil pumps, the bearings, the cam gears and so on were all designed with that specific oil in mind, not the other way around. So that's my take on the choice of TWS. It was actually chosen in the 1990's by BMW Motorsport and adopted by the M Division for production cars. "We need a 10w-60" probably never crossed anyone's mind. "We're using TWS" settled it.

 

[AEHaas]

The Ferrari Enzo was "designed" around the Shell 10W-60 oil and all Ferraris for some years now are spec'ed for Shell lubricants. The 10W-60 almost immediately thins to a 40 grade oil in real use. To me a stable 40 grade oil that holds grade would be better. While the Shell products are "certified" for Ferrari use I have used Mobil 1, Renewable Lubricants, Red Line and Castrol products for motor oil, gear oil, diff and transmission fluids. Actually, over the years, anything But Shell. I have done this with carnal knowledge of the tech people of Ferrari North America. Once there was even a lubricant warrantee issue where a new transmission was offered to me despite the admitted use of Red Line instead of Shell fluids. I declined the offer to replace the transmission in my new Maranello 575 by FNA. We then became best friends. If anybody had a lubricant that was "required" by engine design it would be Ferrari. If you visit the factory campus there are more areas off limits to ANYBODY because they are related to racing secrets. I have some connections here, all I can say. The point is that most people talk about motor oil, many usually limit it to some viscosity, then ignore the many other aspects involved. In my experience the rate of engine wear is most directly related to the amount of dirt in the oil and catastrophic wear is most often related to oil starvation. Viscosity is just not that important yet all we talk about here. aehaas

 

[CATERHAM]

Originally Posted By: AEHaas

Viscosity is just not that important yet all we talk about here. aehaas

Or more to the point, a high viscosity is simply not necessary or desirable in most applications, especially for street use. Regarding Ferrari, I believe Shell Ultra 5W-40 (HTHSV 3.68cP, 180 VI), not a particularly heavy oil, is what's been spec's for quite a few years now for all street models.

 

[jaj]

Originally Posted By: AEHaas

The Ferrari Enzo was "designed" around the Shell 10W-60 oil and all Ferraris for some years now are spec'ed for Shell lubricants. The 10W-60 almost immediately thins to a 40 grade oil in real use. To me a stable 40 grade oil that holds grade would be better...

You see, that's where we differ. I believe that both BMW and Ferrari know perfectly well what viscosity their selected oils become after use - TWS becomes a 5w-50 and Helix Ultra 10w-60 becomes a xw-40. They have known that for a decade or longer. The reason they chose those specific oils is because of all the other things about them that "just works" in the engine families they're used in. For both of these exceptionally skilled engine companies, viscosity rating is a labeling issue, not a performance concern.

 

[semaj281]

Originally Posted By: jaj

You see, that's where we differ. I believe that both BMW and Ferrari know perfectly well what viscosity their selected oils become after use - TWS becomes a 5w-50 and Helix Ultra 10w-60 becomes a xw-40. They have known that for a decade or longer. The reason they chose those specific oils is because of all the other things about them that "just works" in the engine families they're used in. For both of these exceptionally skilled engine companies, viscosity rating is a labeling issue, not a performance concern.

If they knew well what their recommended oils become during/after service, then it's safe to say there were other factors involved in making a recommendation; other factors being marketing, and symbiotic relationships between the auto manufacturer and the oil company.

 

[virginoil]

Originally Posted By: CATERHAM

No disagreement from me. And in the same thread the discussion continued: http://www.bobistheoilguy.com/forums/ubb...298#Post2481298 The grade on the bottle is the starting point, but if you really want to compare the initial expected viscosities of a bottle of oil and how it will behave in your engine, the viscosity spec's to compare are HTHS and the viscosity index. Oils with the same HTHSV and VI will have identical operational viscosities; i.e., the same oil pressure at all oil temp's generally above 0C. That's at least initially. An oil's propensity to shear once it is in service is another matter.

All the information you quote is great and that's one of my layman reasons why the OEM builder approval is important to me, as I assume all the stuff you write about is checked out by the OEM, under various operating conditions, before it is endorsed for the engine question.

 

[Jim Allen]

Originally Posted By: JHZR2

[quote=AEHaas] So while I concur with your claim, I think that for the most part, statistically significant information has suitably indicated a non-issue using the specified lube for the specified interval in ones' engine. That doesnt mean to pack up shop and go home, but it does generally mean that using the recommendation is a fair approach that has been successful, and optimization, if any, is generally done more for sport/hobby than to see practical longevity improvements.

JHZR2: Nail on the head, I think. When you get right down to it, we are all pretty cheeky thinking we can outdo the many engineers and many hours of tests involved with selecting the oil for our engines. I think we get away with it because, a) there is so much leeway (including for idiocy) built in, b) we generally don't operate our engines under severe stress. In a few cases, we might be able to optimize for a particular situations that's a little outside the box, or find substitute products. As you learn a bit more about lubrication, I think it's natural you want a more fine measurement on things. The existing system seems pretty clunky but if you think back to before you knew anything... you can acknowledge that you wouldn't really want it any more complicated than it is. Dr Haas: Looks like your flack jacket was not needed today! Classic BITOG, Gentlemen!

 

[jaj]

Originally Posted By: semaj281

...If they knew well what their recommended oils become during/after service, then it's safe to say there were other factors involved in making a recommendation; other factors being marketing, and symbiotic relationships between the auto manufacturer and the oil company.

Agreed. "Performance" is on the list too, but I'm sure if BMW switched to Mobil from Castrol, Mobil wouldn't have any problem formulating a replacement for TWS. There is an example of such a change happening right now, as Dodge/Chrysler switches from Mobil to Shell. Fiat and Shell are partners, so Mobil loses out.

 

[Coprolite]

I agree with the whole spirit of this thread. My Nissan VQ has evolved with the strong recommendation for "Nissan Ester" 5w30 for various reasons. This oil doesn't stand up very well to the shear of the engine and, more often than not, ends up in the 20 range. If Nissan is willing to warranty an engine with that oil, I am willing to use any light Xw30, even if it is known to shear down. That is even a potential benefit, as the sheared down Nissan oil gave better fuel economy than the new 5w30 that replaced it.

 

[Solarent]

Originally Posted By: Jim Allen

As you learn a bit more about lubrication, I think it's natural you want a more fine measurement on things. The existing system seems pretty clunky but if you think back to before you knew anything... you can acknowledge that you wouldn't really want it any more complicated than it is.

+1 Jim I concur! I would also add that it doesn't take long to learn the basic principles and that makes you so far ahead of where you were before that it's easy to think you know everything - or at least come across that way on an online forum. That's one of the things I love about working with oil products all the time; it's a constant learning process and even though the industry and oil consumer culture is inundated with longstanding traditions there is always something around that makes us go hmmmm....

 

[mechtech2]

AEHAAS- In racing, it is not the dirt, but low viscosity that will puke an engine. And for street cars, ever hear that most wear occurs at start up? Is this because dirt is more present then?

 

[CATERHAM]

Originally Posted By: jaj

Originally Posted By: AEHaas

The Ferrari Enzo was "designed" around the Shell 10W-60 oil and all Ferraris for some years now are spec'ed for Shell lubricants. The 10W-60 almost immediately thins to a 40 grade oil in real use. To me a stable 40 grade oil that holds grade would be better...

You see, that's where we differ. I believe that both BMW and Ferrari know perfectly well what viscosity their selected oils become after use - TWS becomes a 5w-50 and Helix Ultra 10w-60 becomes a xw-40. They have known that for a decade or longer. The reason they chose those specific oils is because of all the other things about them that "just works" in the engine families they're used in. For both of these exceptionally skilled engine companies, viscosity rating is a labeling issue, not a performance concern.

And BMW (M series) and Ferrari expect their cars to be possibly tracked or driven all day at high speeds on the autobahn where high oil temp's likely will occur. Therefore the specified oil must take that into consideration at the expense of cold temperature flow. Dr. Haas has never tracked his Enzo nor driven it over 100 mph (I know it's hard to believe) but he does know something about motor oil. Driven in such a conservative manner the Enzo's oil temp's even in the State of Florida never exceeds a rather cool 82C. He also knows that oil pressure is the bottom line. So he's taylored his oil choice to his own application. Haas is not unlike many NA high performance and exotic car owners who love their rolling art and racy tuneful engines; they just don't drive fast. But many will rev the snot out of a cold engine for the musical delight often with disasterous results on the spec' 10W-60 oil. BMW has a variable tach red line to deal with the problem but Ferrari's don't, nevertheless it can be a royal pain every time you take one of your toys out for a spin to wait for the very heavy "race oil" to thin out adequately before you can safely extract full power. IFAIK Ferrari hasn't spec'd the 10W-60 grade for quite a few years now and only BMW still does for mass produced cars.

 

[HTSS_TR]

I agree. Dr. Haas knows something about motor oil and tailored his oil choice to his own application.