oil viscosity and regulatory influence
#1
06-17-2015, 09:40 PM
oil viscosity and regulatory influence
The link below leads to an article at Machinery Lubrication Magazine:
Motor Oils - Fuel Economy vs. Wear
Overall, it supports the argument that the major factor driving the
recent trend to ever lower oil viscosity specifications are government
mandates regarding fuel economy.
Notice that the driving force is fuel economy and not engine protection.
I have pointed out that Jaguar uses "for best fuel economy" in their
oil viscosity recommendations page in other postings.
Auto manufacturers, on the other hand, are concerned about fuel economy.
The manufacturer faces big fines if the fleet of cars it produces falls
short of the Corporate Average Fuel Economy (CAFE) requirements imposed
upon them by the federal government.
Thinner oils are being used these days for three reasons: They save fuel
in test engines, the viscosity rules have changed, and manufacturers are
recommending thinner grades.
Viscosity and Wear
Thinner oils have less drag, and therefore less friction and wear.
Right? Perhaps in the test engine or engines that experience normal
operation. But somewhat thicker oils may offer more protection for more
severe operations such as driving through mountains, pulling a boat,
dusty conditions, short trips, high rpm, overloading, overheating and
overcooling.
...
To determine if SAE 5W-20 oils provide the same level of protection as
SAE 5W-30 oils, Dagenham Motors in England, one of the largest Ford
dealers in Europe, was consulted. SAE 5W-30 is required for warranty
purposes in England, and SAE 5W-20 is not even available. If SAE 5W-20
were better for both fuel economy and wear, why would Ford not recommend
it for its same engines in Europe?.
and finally the article gets to:
As a bonus, see the picture of Shell Rotella in action
The source article is:
Oil Viscosity: How Low Can You Go? - Article - TruckingInfo.com
Other tidbits encountered included:
-- oxidation of oil doubles for every 10*C increase in temperature
-- the optimal oil temperature when considering wear is somewhere between 180*F and 200*F
If you have a disagreement with the quotes above, they are quotes from a larger
article, so please have the courtesy to read and consider the article in its
entirety. Also note that your disagreement would be with the author of the
article and not me. This is irrespective of the fact that I happen to agree
with the article. Also bear in mind that the content of the article is in
agreement with a number of other articles by oil industry insiders and
academics. I deliberately stayed away from forums, marketing sites and such
due to the influence of "marketing repeated as gospel" by "instant internet experts".
The articles are already linked, and other information can be found on ones own
by searching, so I will not respond to trolls asking for "citations". This is
not a thesis review committee meeting.
All of this "stuff" was unearthed while researching optimum oil temperature
in concert with considering a 160*F coolant thermostat which was shipped in error
after ordering a 176*F thermostat. The result of that will be the subject of
another post.
++
Motor Oils - Fuel Economy vs. Wear
Overall, it supports the argument that the major factor driving the
recent trend to ever lower oil viscosity specifications are government
mandates regarding fuel economy.
Notice that the driving force is fuel economy and not engine protection.
I have pointed out that Jaguar uses "for best fuel economy" in their
oil viscosity recommendations page in other postings.
Auto manufacturers, on the other hand, are concerned about fuel economy.
The manufacturer faces big fines if the fleet of cars it produces falls
short of the Corporate Average Fuel Economy (CAFE) requirements imposed
upon them by the federal government.
Thinner oils are being used these days for three reasons: They save fuel
in test engines, the viscosity rules have changed, and manufacturers are
recommending thinner grades.
Viscosity and Wear
Thinner oils have less drag, and therefore less friction and wear.
Right? Perhaps in the test engine or engines that experience normal
operation. But somewhat thicker oils may offer more protection for more
severe operations such as driving through mountains, pulling a boat,
dusty conditions, short trips, high rpm, overloading, overheating and
overcooling.
...
To determine if SAE 5W-20 oils provide the same level of protection as
SAE 5W-30 oils, Dagenham Motors in England, one of the largest Ford
dealers in Europe, was consulted. SAE 5W-30 is required for warranty
purposes in England, and SAE 5W-20 is not even available. If SAE 5W-20
were better for both fuel economy and wear, why would Ford not recommend
it for its same engines in Europe?.
What To Use
Although thinner oils with less antiwear additive outperform more robust
products in the 96-hour fuel economy test, it is not clear that such
products save fuel over the useful life of the engine.
...
The best protection against wear is probably a product that is a little
thicker (such as SAE 10W-30 or 15W-40) and has more antiwear additives
than the oils that support the warranty.
Although thinner oils with less antiwear additive outperform more robust
products in the 96-hour fuel economy test, it is not clear that such
products save fuel over the useful life of the engine.
...
The best protection against wear is probably a product that is a little
thicker (such as SAE 10W-30 or 15W-40) and has more antiwear additives
than the oils that support the warranty.
As a bonus, see the picture of Shell Rotella in action
The source article is:
Oil Viscosity: How Low Can You Go? - Article - TruckingInfo.com
Other tidbits encountered included:
-- oxidation of oil doubles for every 10*C increase in temperature
-- the optimal oil temperature when considering wear is somewhere between 180*F and 200*F
If you have a disagreement with the quotes above, they are quotes from a larger
article, so please have the courtesy to read and consider the article in its
entirety. Also note that your disagreement would be with the author of the
article and not me. This is irrespective of the fact that I happen to agree
with the article. Also bear in mind that the content of the article is in
agreement with a number of other articles by oil industry insiders and
academics. I deliberately stayed away from forums, marketing sites and such
due to the influence of "marketing repeated as gospel" by "instant internet experts".
The articles are already linked, and other information can be found on ones own
by searching, so I will not respond to trolls asking for "citations". This is
not a thesis review committee meeting.
All of this "stuff" was unearthed while researching optimum oil temperature
in concert with considering a 160*F coolant thermostat which was shipped in error
after ordering a 176*F thermostat. The result of that will be the subject of
another post.
++
The following 2 users liked this post by plums:
Grant Francis (06-18-2015),
yarpos (06-23-2015)
#2
06-18-2015, 01:24 AM
Veteran Member
Thicker oils are all very well, except for the parts that need thinner (such as VVT), so I suppose it's a balance and there will be reports that disagree - some of which will be suppressed as the tobacco industry and pharma did/do. Comes down to individuals either following OE recommendations or their own beliefs.
Seems nothing changes....
The bit about oxidation is chemistry 101. It's a rule of thumb that the rate of reaction doubles for each 10C rise.
I don't really get its relevance since it's the contamination with engine byproducts that matters most, at least so I've understood.
Seems nothing changes....
The bit about oxidation is chemistry 101. It's a rule of thumb that the rate of reaction doubles for each 10C rise.
I don't really get its relevance since it's the contamination with engine byproducts that matters most, at least so I've understood.
Last edited by JagV8; 06-18-2015 at 01:28 AM.
#3
06-18-2015, 05:16 AM
Neither of those are good in oil.
Not everyone has VVT, and the remarks are not specific to Jaguar.
In my case, no VVT as none of the SC models use VVT.
Even with VVT, I doubt adopting a 10W30 in place of a 5W30 would
have any negative effects.
This is what Jaguar has to say:
SAE Viscosity Rating: For climates ranging from –30°C (–22°F) and +50°C (+122°F), the following oil viscosities may be used:
0W–30 5W–30 (preferred)
0W–40 5W–40
0W–30 5W–30 (preferred)
0W–40 5W–40
Anecdotally, my particular unit is much quieter on Shell Rotella 15W40 conventional as compared to Shell Rotella 5W40 full synthetic.
Oh, btw:
I don't really get its relevance since it's the contamination with engine byproducts that matters most, at least so I've understood.
out that due to vapor pressure of the contaminants, including water, it is not necessary
to "boil" the water off. It is simply necessary to reach some reasonable temperature.
Those that insist that the oil has to be at the boiling point of water would be ignoring
other contaminants with different boiling points.
A chart from that source as well as the text shows a rise in oil degradation from
various factors on either side of the 80*C sweet spot. They have designed their
oil monitoring algorithm accordingly.
++
Last edited by plums; 06-18-2015 at 05:23 AM.
The following users liked this post:
o1xjr (06-18-2015)
#4
06-23-2015, 03:00 AM
update
From a current academic publication dated 2015:
The 0W20 specified is actually very much like the best 0W20 oils in the PCMO
market. The oil it was being compared to is a special formulation which could
never meet the current oil specs because it violates some of the classification
parameters.
The conclusion really ought to be that physical and mechanical laws have really
not changed much since the original derivation of the regulating equations.
Therefore, deviating from well known solutions to the limitations means deviating
from what has already been known for many decades to be the optimal solutions.
For example, lubrication film thickness requirements for journal bearings have
finite limits for adequacy. If you know what the number happens to be, then
you can easily see that an oil viscosity of any particular value would or would
not be reasonabley adequate.
Now, if the published viscosity classification limits preclude a particular SAE
viscosity grade from meeting the mechanical requirements, then no argument
about fuel economy is ever going to change that. Simply put, if the vendor
recommended grade is precluded by specification from meeting the mechanical
requirements, the vendor has guaranteed the likelihood of metal on metal
contact in operation for anyone following the recommendation.
The vendor meets CAFE targets and gets a bonus of selling more cars.
Sounds like a win-win ... except for an enthusiast buying used cars and
hoping to keep them alive for a long time.
++
A more common 0W20 oil with a HTHS-viscosity of 2.8 mPa s achieves the same friction reduction, but shows the presence of metal-metal contact for full load operation. This metal-metal contact might be able to be addressed by suitable additive technology of the lubricant or alternative surface technology for the shaft or bearing.
market. The oil it was being compared to is a special formulation which could
never meet the current oil specs because it violates some of the classification
parameters.
The conclusion really ought to be that physical and mechanical laws have really
not changed much since the original derivation of the regulating equations.
Therefore, deviating from well known solutions to the limitations means deviating
from what has already been known for many decades to be the optimal solutions.
For example, lubrication film thickness requirements for journal bearings have
finite limits for adequacy. If you know what the number happens to be, then
you can easily see that an oil viscosity of any particular value would or would
not be reasonabley adequate.
Now, if the published viscosity classification limits preclude a particular SAE
viscosity grade from meeting the mechanical requirements, then no argument
about fuel economy is ever going to change that. Simply put, if the vendor
recommended grade is precluded by specification from meeting the mechanical
requirements, the vendor has guaranteed the likelihood of metal on metal
contact in operation for anyone following the recommendation.
The vendor meets CAFE targets and gets a bonus of selling more cars.
Sounds like a win-win ... except for an enthusiast buying used cars and
hoping to keep them alive for a long time.
++
#5
06-23-2015, 03:09 AM
did you know?
A prime example of specification gamesmanship is actually the AJxx series
of engines.
In the same year and version(AJ26/AJ27), US, Mexico and Europe all get
their own manufacturer recommended SAE grades. The US gets the lightest.
The US also has CAFE. As someone put it on another forum: somehow the
engines transform themselves crossing the Atlantic.
It gets better.
When the AJxx V8's are used in Land Rovers, they get beefier oil recommendations
in the US market. Same engine, same climate ... different oil.
And the penultimate example ...
When the AJxx V8 derived engine is assembled in Cologne for use in an Aston Martin,
the oil recommendation is a whopping and expensive Castrol only, restricted availability,
10W60 European spec synthetic. Unobtainium in the US, so the substitute is the same
grade Castrol oil only available to BMW dealers for servicing certain M series BMW vehicles. Something like $20/quart.
So ... Walmart 5W30 for Jaguar owners and Castrol 10W60 full synthetic for Aston Martin
Vantage owners.
Can we have a chorus of WTF here?
++
of engines.
In the same year and version(AJ26/AJ27), US, Mexico and Europe all get
their own manufacturer recommended SAE grades. The US gets the lightest.
The US also has CAFE. As someone put it on another forum: somehow the
engines transform themselves crossing the Atlantic.
It gets better.
When the AJxx V8's are used in Land Rovers, they get beefier oil recommendations
in the US market. Same engine, same climate ... different oil.
And the penultimate example ...
When the AJxx V8 derived engine is assembled in Cologne for use in an Aston Martin,
the oil recommendation is a whopping and expensive Castrol only, restricted availability,
10W60 European spec synthetic. Unobtainium in the US, so the substitute is the same
grade Castrol oil only available to BMW dealers for servicing certain M series BMW vehicles. Something like $20/quart.
So ... Walmart 5W30 for Jaguar owners and Castrol 10W60 full synthetic for Aston Martin
Vantage owners.
Can we have a chorus of WTF here?
++
Last edited by plums; 06-23-2015 at 03:14 AM.
#6
06-23-2015, 03:48 AM
and the practical application
The contingent from the southern hemisphere following this
can probably ignore this and just nod sagely. They seem to
already know what is coming because reputedly the most
popular grade of oil sold in AU/NZ is 10W50.
It so happens that xxW50 is the closest grade according to
the limitations of the mechanical laws mentioned above that
allows best protection against wear. Fuel economy being a
distant and irrelevant consideration in a private hands.
The locally available choices boiled down to:
a) Castrol Syntec Edge 0W40 A3/B4 European
b) Castrol Syntec Edge 5W50 Classic Car
c) Shell Rotella T6 5W40
All are fairly close when their viscosity is graphed except at the very extremes
of the temperature range.
The pick this time around went to (b) on a whim because it has a slight edge
at the top end of the temperature range.
The Rotella in (c) would be a very good alternative, and for longevity, it would
probably push the Castrol aside handily.
Having been a long time user of Castrol GTX 20W50, and a recent user of 15W40,
I am certain of the ability to start in subzero temperatures, so (a) got returned
to the store in favour of (b) after examining plots of the respective viscosity
curves. On the other hand, if someone wants the equivalent of the fabled German
Castrol 0W30, but in 0W40, then (a) is definitely their pick. Make sure it says
"Made in Belgium" on the back of the jug.
As for the oft claimed advantage of startup wear reduction with a lighter xxW,
that is for the most part a placebo effect. To understand why, just view a
viscosity graph of the selected oils.
++
can probably ignore this and just nod sagely. They seem to
already know what is coming because reputedly the most
popular grade of oil sold in AU/NZ is 10W50.
It so happens that xxW50 is the closest grade according to
the limitations of the mechanical laws mentioned above that
allows best protection against wear. Fuel economy being a
distant and irrelevant consideration in a private hands.
The locally available choices boiled down to:
a) Castrol Syntec Edge 0W40 A3/B4 European
b) Castrol Syntec Edge 5W50 Classic Car
c) Shell Rotella T6 5W40
All are fairly close when their viscosity is graphed except at the very extremes
of the temperature range.
The pick this time around went to (b) on a whim because it has a slight edge
at the top end of the temperature range.
The Rotella in (c) would be a very good alternative, and for longevity, it would
probably push the Castrol aside handily.
Having been a long time user of Castrol GTX 20W50, and a recent user of 15W40,
I am certain of the ability to start in subzero temperatures, so (a) got returned
to the store in favour of (b) after examining plots of the respective viscosity
curves. On the other hand, if someone wants the equivalent of the fabled German
Castrol 0W30, but in 0W40, then (a) is definitely their pick. Make sure it says
"Made in Belgium" on the back of the jug.
As for the oft claimed advantage of startup wear reduction with a lighter xxW,
that is for the most part a placebo effect. To understand why, just view a
viscosity graph of the selected oils.
++
Last edited by plums; 06-23-2015 at 03:51 AM.
#7
06-24-2015, 12:09 AM
Veteran Member
Thanks for any interesting series of posts. I have been non compliant with Toyota's VVT recommendation for 400k kms and counting using Caltex 15W40 in a light truck. Personally I think in a generally benign environment like Australia it doesnt matter that much, and whatever you use, just change it reasonably often and you should be good over a normal span of car ownership.
Trending Topics
#8
06-27-2015, 03:12 AM
Thanks for any interesting series of posts. I have been non compliant with Toyota's VVT recommendation for 400k kms and counting using Caltex 15W40 in a light truck. Personally I think in a generally benign environment like Australia it doesnt matter that much, and whatever you use, just change it reasonably often and you should be good over a normal span of car ownership.
#9
06-27-2015, 03:22 AM
from the home office
Quoting someone on the UK site:
Cooler climate, heavier oil. Same engine.
But the UK didn't have CAFE to contend with.
Mexico is a hotter climate and warranty requirements are
xxW40 or xxW50 full synthetic. No CAFE.
There is no evidence that the engines have any mechanical
differences from market to market of the same model year.
Therefore, requirements for optimal lubrication at operating
temperature ought to be the same.
Makes one say hmmm....
++
My XK8 is a 1999 4.0L. I talked to Jaguar Customer Assistance before my last oil change and they suggested talking to Castrol Tech Centre in Swindon. The recommended oil for this engine in our UK climate is Castrol Magnatec 10W-40. The manual says that a 5W-40 or a 10W-40 is good for a temperature range of -20 to +50C, but the 4.0L engine is classed as an 'older spec' which needs an A2 (normally-aspirated) or A3 (supercharged) grade product. Apparently you should not use an A1 grade oil in an older spec car
But the UK didn't have CAFE to contend with.
Mexico is a hotter climate and warranty requirements are
xxW40 or xxW50 full synthetic. No CAFE.
There is no evidence that the engines have any mechanical
differences from market to market of the same model year.
Therefore, requirements for optimal lubrication at operating
temperature ought to be the same.
Makes one say hmmm....
++
Last edited by plums; 06-27-2015 at 03:24 AM.
The following users liked this post:
Grant Francis (02-15-2016)
#10
02-15-2016, 06:11 PM
continuued below with information published by Jaguar:
https://www.jaguarforums.com/forum/x...idance-157906/
https://www.jaguarforums.com/forum/x...idance-157906/
#11
05-14-2016, 01:33 AM
it is rumoured:
I've been following topics relating to 5w20 oils for a while
with regards to various makes and models. The most enlightening
post I have seen was made by an (I believe Ford) engineer
involved in oil testing. He went so far as to say that while 5w20's
protection was considered acceptable, and resulted in a 1% or so
increase in MPG, which is good for the manufacturer's CAFE, that
actual wear was significantly greater for 5w20 than for 5w30. And
that he, personally, did not use 5w20 for that reason.
with regards to various makes and models. The most enlightening
post I have seen was made by an (I believe Ford) engineer
involved in oil testing. He went so far as to say that while 5w20's
protection was considered acceptable, and resulted in a 1% or so
increase in MPG, which is good for the manufacturer's CAFE, that
actual wear was significantly greater for 5w20 than for 5w30. And
that he, personally, did not use 5w20 for that reason.
#12
05-14-2016, 03:58 AM
Veteran Member
Thread
Thread Starter
Forum
Replies
Last Post
FS[MidAtlantic]: 1997 XJ6 VDP $3,900 - Very RARE Anthracite on Warm Charcoal
42Ajd
PRIVATE For Sale / Trade or Buy Classifieds
0
09-26-2015 07:04 PM
Woznaldo
XJ6 & XJ12 Series I, II & III
9
09-26-2015 11:02 AM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)