DougWantsALeaf
Well-known member
Ok, will wait for the update, but if you can even get .1 miles/kWh gain, it's certainly worth the change.
Reduction Gear Oil Change - Benefits for Range
- Thread starter knightmb
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One data point does an anecdote makeknightmb said:
Your result is unlikely to pass the sniff test. It implies that one well lubricated gear with older oil is generating about 30 watts more than with new oil. I'll believe a 1% difference, so about 3-4 watts.
SageBrush said:
I agree with your 1% guess in our Leaf gears. .... For comparison---> In ICE cars, the difference between using a 5w-30 oil vs. a thinner 0w-20 in the engine is around a 1.5% fuel efficiency difference. .. ( This has long been studied, lots of data on 5w-30 vs. 0w-20 in car engines, and the range of difference varies depending on the application, expected 0.5% to 3% is a normal range of energy efficiency gains going to thinner stuff.)
However, knightmb has been getting repeated results, not just one or two times over the same routes, but several so far (more to come).
From the last recent thread on this subject, repeated here to show the last result wasn't just a flash in the pan:
knightmb said:
knightmb
Well-known member
SageBrush said:
I agree, I did have some other data points (actually a lot more if I really just put the entire month of April into a spreadsheet and then start doing a comparison of every route that is the same) but I don't want to give people the idea that this is an EV panacea. I was going to "experiment" on a family member Gen 1 Leaf. They gave me permission to do some before and after testing using the same ULV that I used. Funny thing is, I went to buy some more ULV online and Walmart was out of stock? Then I tried Advanced Auto, also out of the stock? WTF? I hope everyone isn't rushing out to buy this and pour it into their Leaf because the last thing we need is a bunch of busted gear boxes in a few years if things are too good to be true. I did finally find a single store in the area that had 1 qt left (which is all I need since I still have half of another previous bottle). Hopefully I haven't started a bad trend.... :shock:
knightmb
Well-known member
voltamps said:
In the spirit of that, I am in contact with a Professor at Tennessee Tech, he actually organizes and hosts a lot of EV events to help get the word out to the public with his students and interns. Last time I talked to him, told him that I found something that might be a cheap way to increase EV range and that I needed something of a more concrete study to see if it is really making a usable difference. He was very interested in it, so maybe I can get a real university study done on this ULV gear oil subject with some real scientific testing to back up the research. At least it would be able to nail down some hard numbers like how much it helps or does not help (in the event that it is just tearing up the gearbox). Time will tell..
A simple temperature test would be enough:
Measure baseline temp of the oil
Take your hour drive at 70 mph
Measure oil temp
Oil volume is ~ 1400 ml
Specific heat of oil is ~ 2 joules/ml*K
I don't know how much oil heat is dissipated but your presumption of 30 watts energy savings implies ~ a 40C decrease in oil temp without dissipation. It should not be a subtle change. In fact, your new oil may freeze.
And all that without a change in viscosity per your Blackstone tests.
As I said, this does not pass the sniff test.
----
Oddly enough, I think I'll replace my ATF today if the weather is nice. But not for efficiency, but because the LEAF is at 40k miles and I don't even want to think about future gearbox wear. I hope this is the last oil change I ever do. I plan to buy a Castrol product named Castrol Transmax Import Multi-vehicle instead of the 3x priced Nissan Matic-S. ATF nerds say it is the same stuff and I think it is available at my local Walmart.
Measure baseline temp of the oil
Take your hour drive at 70 mph
Measure oil temp
Oil volume is ~ 1400 ml
Specific heat of oil is ~ 2 joules/ml*K
I don't know how much oil heat is dissipated but your presumption of 30 watts energy savings implies ~ a 40C decrease in oil temp without dissipation. It should not be a subtle change. In fact, your new oil may freeze.
And all that without a change in viscosity per your Blackstone tests.
As I said, this does not pass the sniff test.
----
Oddly enough, I think I'll replace my ATF today if the weather is nice. But not for efficiency, but because the LEAF is at 40k miles and I don't even want to think about future gearbox wear. I hope this is the last oil change I ever do. I plan to buy a Castrol product named Castrol Transmax Import Multi-vehicle instead of the 3x priced Nissan Matic-S. ATF nerds say it is the same stuff and I think it is available at my local Walmart.
Not that Castrol fluid. It's too thick. It won't hurt your gearbox, but range will go down some. Runs a tad hotter with all that extra viscous drag. Not destructively, certainly OK for wear, but not what Nissan engineers have recommended.SageBrush said:
Castrol Transmax Import Multi-Vehicle is kv100 7.4, 40% higher than Nissan Matic S kv100 5.2, and remember it will be divergently thicker for any cooler temperatures too.
At Walmart or autoparts store, I'd say pick any "Dexron VI or Mercon LV" (the kind Teslas use) equivalent-compatible fluid you see on the shelf and it's only 20% thicker kv100 than Matic S. .... Valvoline MaxLife MultiVehicle fluid is a good choice at kv100 5.9, solid quality too. Any brand really is fine. Off-the-shelf ATFs are all using at least GroupIII base oils for good longevity. (Getting GroupIV ATF means mail-order bother.)
If you see "Dexron HP" type fluid, which is what Chevy Bolts use, that one lasts the longest, by it's performance spec, compared to any on the shelves (outside of Amsoil SS or Redline D6 which are usually mail order.) Dexron HP is about kv100 5.8, so it's a good Nissan Matic S replacement there.
If you can, please take a pic of the magnets. The 'gold standard' picture so far is estomax's Redline D6 magnets with barely any metal on them, if you don't count the other example from a Driving School where they babied the accelerator pedal & got very little metal too with the original Matic S factory fill. My magnets at only 1,400 miles on new-ish Leaf showed some metals, due to break-in polishing & my lead foot.
That's the problem, we don't know what the variable heat flux (heat transfer) is through the aluminum housing is to say where the temperature would end up at. Energy (kWH) usage per mile kind of gets right to the point already.SageBrush said:
This reminds me of a couple of guys I knew a few years ago, one thru the local SAE group, who was hired by Toyota to simulate (model) the heat transfer dynamics of the 2nd-gen Prius power electronics box. He said his virtual model was pretty close to simulating reality anyway, but there was nothing like rigging small temperature sensors, with some granularity, around the box, and then the model was corrected to more accurately look for hot spots between the temperature sensors. .... Another fellow I worked with had just finished up a consulting project for Mercedes to model under-hood engine air-flow & heat transfer characteristics (in the M-Class SUV), again, like in the Prius case above, looking for hot spots that might of course cause warranty & recall problems for Mercedes, and he said about the same thing as the Prius guy.
I've never virtual-modelled heat transfer projects, only F=MA & structural finite element, NVH, etc.... Heat transfer has similar partial differential equations, except the flux topography is usually complicated. Engineers 50 years ago simplified & interpolated A LOT.
@voltAmps,
I may have posted the wrong Castrol ATF
What is your opinion of Transmax Full Synthetic Multi-Vehicle ATF ?
Here is its spec sheet
https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/9D55991CEA3A07B8802582950058695F/$File/BPXE-ASHVBS.pdf
Kinematic viscosity is 5.9 and 30.2 Cst at 100C and 40C, respectively.
---
As an aside, if viscosity is proportional to friction it emphasizes the importance of standardizing initial oil temperature test conditions.
I may have posted the wrong Castrol ATF
What is your opinion of Transmax Full Synthetic Multi-Vehicle ATF ?
Here is its spec sheet
https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/9D55991CEA3A07B8802582950058695F/$File/BPXE-ASHVBS.pdf
Kinematic viscosity is 5.9 and 30.2 Cst at 100C and 40C, respectively.
---
As an aside, if viscosity is proportional to friction it emphasizes the importance of standardizing initial oil temperature test conditions.
denwood
Well-known member
voltamps said:
That was my car purchased used from a local Driving School. The oil change was last week at about 37 000 miles. I know the owner did not baby the car (the tires were done!) and he only ran the OEM tires for half the year, winters the rest. You are correct though in that much of the mileage was put on by students, the car saw mostly urban use (we are a small town of 100K), and our climate is cool. In that case, the LEAF never saw extended highway use in heat. I didn't take a macro shot of the plug magnets, but to my naked eye, there was nothing there of note with respect to metal.
There is not much in the way of moving parts in the LEAF, so the loss there is also not large. I'd be shocked and amazed if the Redline D6 in there has any measurable effect on efficiency for urban use. It's only folks doing the long distance, higher speed trips that would likely be able to measure any difference at all...and that's assuming that what we're replacing the S-Matic with something that is measurably any better. I've found marketing vs fact a tough nut when we're talking oil
That said, it 100% bears a study as we're all interested in getting to the very last mile on these EVs. Just don't turn on the heat..ha I very much appreciate the hard data posted in this thread.I did a ton of observations in this area after doing an Audi i4 conversion into at 1990 VW Westfalia. I designed a rear fender oil cooler, blueprinted the oil pump, added a factory windage tray (crankcase) and even added an Accusump pre-oiler. VDO gauges for oil pressure and temp were added, so I was able to figure out a lot with respect to temps, pressures, ... including a drop to 5w30 for the vehicle (well below the recommendations) in summer to gain efficiency. My focus there was longevity vs efficiency (we're talking a Westfalia camper here) but there were certainly pumping loss gains going to thinner oil, and very measurable temperature drops when all was dialled in correctly with synthetic. In that case we're talking about a much more complicated engine model with oil pump, all the moving bits, oil channels, bearing clearances, piston squirters, etc. In the end, the van could do 0-60 in 13 seconds (vs the OEM of 20.5 s, yikes) and got up to 27 mpg (23 US, about 20% over OEM) on the highway. The LEAF final drive physics model at play here is vastly simpler.
Good ATF there for a Leaf. I do have a slight preference for Valvoline MaxLife MultiVehicle Full Synthetic over the Castrol, since the Valvoline actually ends up being 40 cSt thinner at 32F (0C) to help range when first starting out in the winter. Either is fine. Both are in the usual Dexron VI class. Its hard to go wrong getting a name-brand DexronVI-class ATF for a Leaf.SageBrush said:
Visc is proportional to friction until one goes too thin. If we keep lowering visc, at some point wear & friction start increasing rapidly. How low we can limbo is an unknown. Temperature condition are important, true there.SageBrush said:
Ravenol sums it up best:
"Reducing loss torque in automatic transmissions (ATs) is a key factor in improving fuel economy. A promising approach is to reduce the viscosity of the Automatic Transmission Fluid (ATF) to minimize churning loss. RAVENOL has developed an ultra-low viscosity ATF, called “T-ULV”, which has approximately 50% lower kinematic viscosity at 40 °C compared to the conventional low viscosity ATFs. It is generally understood that if the viscosity of an ATF is too low, it can have a negative impact on the fatigue life of components such as gears and bearings, and possibly lead to increased wear or seizure.
RAVENOL ATF T-ULV Fluid was designed to solve these problems via the application of two key technologies. The first is a high performance PAO (Polyalphaolefin) with a low traction coefficient, which translates to low viscosity under high pressure conditions. This decreases the shear resistance between sliding surfaces under elasto-hydrodynamic lubrication (EHL) conditions, which contributes to improving the fatigue life of bearings and other components. The second is an ester type base oil with high polarity. It was found that the amount of ester base oil used has a major influence on fatigue life. The adsorption of esters onto metal surfaces is thought to improve lubricity in severe lubrication conditions. Durability tests were performed in a wide range of conditions, using gear and bearing components and actual transmission units, and it was confirmed that RAVENOL ATF T-ULV Fluid outperforms low viscosity ATFs, despite its ultra-low viscosity. Furthermore, RAVENOL ATF T-ULV Fluid reduces loss torque in the transmission by approximately 12% compared to other low viscosity ATFs."
https://www.ravenol.de/en/product-range/atf-transmission-fluids-for-automatic-transmissions-1/ravenol-atf-t-ulv-fluid/
Ok, on to the next question: What are the Wh/mile consumption savings in the EPA UDDS cycle ? As in, how much savings for casual city driving where max torque is rare and a limited event ?voltamps said:
Because as it is, 12% max savings with Ravenol on the track is somewhere in the neighborhood of 1 -- 1.5% savings overall.
denwood
Well-known member
SageBrush said:
You really can't use this data unless you assume that the torque converter does not exist. There is gear friction loss, but I'm guessing the behaviour of the fluid in the torque converter may have more to do with this torque gain, than friction between the gears. Gear oil is not a Newtonian fluid so unless there is a mechanical torque converter lock, it is by definition a lossy system. None of these components exist in a LEAF final drive...
SageBrush said:
I don't know. I agree with your estimate of around 1.5% or so. The apparent ~8% reported might be too good to be true.
Ford sure thinks there are some range gains to be had since we recently find out they are using Mercon ULV in their Mach E, the 1st known use of kv100 4.5 type stuff. Ford has to be doing careful metallurgy & heat-treating of the gears, since they know they had to recall my '16 Ford Focus Electric differential spider pinions because Magna (vendor) forgot to heat treat & carbonitride them correctly ! That CAN'T happen on their debut all-Ford EV.
Those involute helical gears, ball bearings, & roller taper bearings don't have a lot of sliding relative-motion friction, it's mostly rolling friction. Pressures are high at low entrainment speeds, collapsing surfing hydrodynamic oil film thickness at those low speeds & high pressures. Tenacious Extreme Pressure (EP) (not to be confused with Tenacious D, a rock band) chemicals in the ATF fluid are the only line of defense in reducing friction at low speed / high torque.
Ravenol and other ULV ATF makers must be boosting EP effectiveness as a way to get the benefit of low visc while not killing gears.
An ICE car's tranny has all that plus losses in the torque convertor grapefruit sections (when unlocked) as denwood said.
I followed @voltAmps suggestion and chose by standard ... and ended up with the Walmart sh1t -- aka SuperTech Dexron - VI, Mercon LV, approved for Matic-S substitution. How bad can it be ? :lol:
I'm not positive but this may be the spec sheet: https://www.schaefferoil.com/documents/267-205A-td.pdf
As an aside, Peakauto.com appears to sell an oil that is very similar if not identical per https://peakauto.com/wp-content/uploads/2017/01/PEAK-ATF-DexronVI-MerconLV-Full-Synthetic-Trans-Fluid-Spec-Sheet-201905.pdf
$6.6 a quart
I'm not positive but this may be the spec sheet: https://www.schaefferoil.com/documents/267-205A-td.pdf
As an aside, Peakauto.com appears to sell an oil that is very similar if not identical per https://peakauto.com/wp-content/uploads/2017/01/PEAK-ATF-DexronVI-MerconLV-Full-Synthetic-Trans-Fluid-Spec-Sheet-201905.pdf
$6.6 a quart
Simpler, yet all the energy rate, power ( = torque x rpm), has to turn the gears in a bath of goopy goo.denwood said:
Every metal surface and tooth must churn it's way thru the ATF fluid, where viscosity defines losses. ....
Taking at look at Sagebrush's youtube posting pic above, it seems obvious they should use counter-sunk torx-head bolts instead of the hex head bolts protruding into the oil flow on the spinning gear face, to reduce rotary drag.
The other thing bad about an EV is all that high torque at very low RPMs which grinds together the meshing teeth.
We don't like high viscosity because the gear bodies swim in it. In the future they could spec thin PAO base oils with esters or other tech, as Ravenol pointed out in my previous post, to work the teeth meshing wear problem.
The gear oil of the future may have kv100 = 1.0 with ionic liquids, polymer esters, and/or other patentable chemicals added to the base oil to increase Range.
Nissan was also known for their Diamond Like Carbon (DLC) engine parts coatings, & I wonder if some kind of smooth hard coating tech could allow lower visc as well.
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