wbusch
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Re: Reduction Gear Oil Change - Benefits for Range

Tue Jul 20, 2021 2:00 pm

The IRS has proposed regs that suggest you must recapture 100% of the credit if it was sold within the first year. Second year 66 2/3% and third year recapture is 33 1/3%

DougWantsALeaf
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Re: Reduction Gear Oil Change - Benefits for Range

Tue Jul 20, 2021 5:39 pm

All
So have we come to any conclusion about the Valvolene ULV oil. Do.we think it runs cooler enough to prevent the aux. Cooling and power draw, hence a .1-.2 miles/kWh improvement in long high-speed scenarios?
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knightmb
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Re: Reduction Gear Oil Change - Benefits for Range

Tue Jul 20, 2021 6:03 pm

DougWantsALeaf wrote:
Tue Jul 20, 2021 5:39 pm
All
So have we come to any conclusion about the Valvolene ULV oil. Do.we think it runs cooler enough to prevent the aux. Cooling and power draw, hence a .1-.2 miles/kWh improvement in long high-speed scenarios?
I haven't put up my final findings yet because I just got access to a 2015 (Gen 1) from a relative a few weeks back, so I'm doing the same battery of test for the coolant, gear oil, etc. to see if there is any difference. Basically, the energy savings is the same as NOT running the climate control, as in AC during hot or warm weather. Thus, it negates the energy penalty of running the climate control. The key is to keep the motor under 140F. It's possible with the stock factory fill if you drive slower (like under 40 mph), but if you want to drive under 70 MPH and keep it in the cool zone, the ULV seems to be the way. The ULV isn't doing anything super special to the gears except helping to keep the temperature just under the mark that sets the cooling system into high mode to cool the motor and electronics. The faster you drive, the closer to the edge you get, so even with the ULV and a lead foot you can still hit the energy penalty with a hot motor. :lol:

That's where the 0.2 savings is coming from, in my opinion based on what I'm seeing during these test. I don't know if this will still be valid during the winter time, but at least for spring, summer, fall driving, I know what I will be doing for friends and relatives driving a Leaf. ;)
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Re: Reduction Gear Oil Change - Benefits for Range

Wed Jul 21, 2021 6:54 am

voltamps has split out the off-topic discussion to this thread: (thanks!)
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Stanton
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Re: Reduction Gear Oil Change - Benefits for Range

Wed Jul 21, 2021 6:55 am

knightmb wrote:
Tue Jul 20, 2021 6:03 pm
The key is to keep the motor under 140F. It's possible with the stock factory fill if you drive slower (like under 40 mph), but if you want to drive under 70 MPH and keep it in the cool zone, the ULV seems to be the way.
That should be easy seeing as I hardly ever drive my leaf > 60 mph (old habits die hard). It seems as though I remember a .4-.5 miles/kWh improvement mentioned earlier in the thread, but no matter: I'll make the change for any documented improvement.
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voltamps
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Re: Reduction Gear Oil Change - Benefits for Range

Sun Jul 25, 2021 6:38 am

Stanton wrote:
Wed Jul 21, 2021 6:55 am
That should be easy seeing as I hardly ever drive my leaf > 60 mph (old habits die hard). It seems as though I remember a .4-.5 miles/kWh improvement mentioned earlier in the thread, but no matter: I'll make the change for any documented improvement.
I was only able to get over 140F degrees (LeafSpy motor/inverter reading) when accelerating hard a lot, or just cruising at 70 mph on a hot day, above about 82F air temp. (Note: Using either Amsoil Signature Series kv100 6.3 or Motorcraft Mercon ULV thin kv100 4.5, about the same for either.)

Hitting the pedal hard flows a lot of amps, and heat in there is proportional to the square of the amps, so it gets hot quick when driving like a maniac. Accelerate normally in traffic like that slow ICE mini-van next to you, and I'd bet you could keep it under 140F most of the time!

About the possible wear issue using thinner ULV oils, Valvoline ULV does have higher levels of anti-wear chemicals than normal thicker ATF fluid, which should help. Also, if running a cooler gearbox can be established here, it'll keep the running viscosity up (oil film thickness up) to help.

I sent a sample of Motorcraft Mercon ULV to a lab for a spectrographic analysis to compare it to the previous @knightmb Valvoline ULV one. Hoping Motorcraft has similar high levels of phosphorus (anti-wear) as Amsoil SS or Valv ULV.
I found a slightly-old RockAuto-Wix kit that should still be good for another lab hit, so off it went. The address was still good on it. Kit was only about 3 years old.
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knightmb
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Re: Reduction Gear Oil Change - Benefits for Range

Tue Jul 27, 2021 12:40 pm

I've had enough time (and some really hot weather) to do some comparison test between my Leaf and a relative (driving a 2015, Gen 1). This is the conclusion I've come up with, totally opinion of course with the limited measuring abilities I have to work with.

I'll start with the 2015 Leaf. For anyone new to the generation names we use here. Usually Generation 1 Leaf are those that have either the 24 kWh or 30 kWh battery packs. This usually covers anything 2017 and older models. I am aware that the replacement batteries for the 30 kWh packs are actually 40 kWh packs *now*, but basically the classic Leaf body design is what I am referring to.

The Gen 1 Leaf is basically limited to 80 kW of power maximum for driving. The gear box is just a single speed reduction gear set that is filled with 1.5 Quarts of Nissan Matic S gear oil from the factory. The Gen 1 Leaf I was experimenting on has a temperature point in the electronics and motor that will switch on the both radiator fans and put the coolant pump into high mode. This temperature appears to be around 140F - 142F (60C - 61C). When the motor+electronics get this hot, an additional power draw of between 600 to 700 watts is used to cool it down. In the grand scheme of things, this is a small percentage of the power used to drive the vehicle.

Knowing that information, how would changing the gear oil have any effect on this? It's actually an interesting case of keeping the motor just cool enough *NOT* to trigger this extra cooling mode. That is where the gear oil change comes in. When the Leaf comes new from the factory, the gears have some "break in" time where they polish each other and in the process, chip off little bits of metal that float around in the gear oil. The Leaf isn't driving an automatic transmission, so those little bits usually get caught by the two magnets inside the gear housing and don't cause any problems. The even tinier bits though that are not magnetic or others that are rust, they diffuse into the gear oil and turn it black basically. The gear oil still functions like it should, but the viscosity is raised a little as more time passes.

Eventually, this increase in viscosity will make the thicker gear oil produce more friction when driving and thus produces more heat. Remember, in the grand scheme of things, this isn't a terrible energy loss. You still drive the Leaf and everything is OK mechanically. This is only 1.5 Quarts of liquid I am referring to. Now, picture this. The Leaf Motor, Electronics, Gears, etc. are all connected to a single "box" of metal. This means that heat can transfer through out the box, which is also fine. That is how the coolant lines keep everything cool. Remember that the gear oil is a source of heat being generated by the friction of gears while driving. That heat will be carried away by the cooling system eventually.

From what I have been measuring, the temperature of the gear oil will eventually surprise the temperature of the motor. When it does, the cooling system must spend power to keep the temperature down. What if you could keep the temperature of the gear oil down low enough as to not trigger the "high" cooling mode of the Leaf and the power penalty that goes with it? That is benefit that I have been recording and watching when doing a gear oil change to ULV (Ultra Low Viscosity) gear oil. This benefit is not limited to just ULV though as I've seen a marginal increase by just changing out the gear oil with the same stuff that Nissan uses to begin with.

The key to it all is the temperature. If you have the ability to use LeafSpy with your Leaf, then on the next drive, watch your motor temperature and see if it frequently goes above 140F. Once it goes above 140F, you'll know that those radiator fans are probably running and your coolant pump is probably running in high mode. If you can keep the temperature down below this, this is where you will see an increase in your range, long term.

My conclusion, changing the gear oil, even with the default Nissan Matic S has a benefit if the existing gear oil was very dirty for Gen1 or Gen2 Leaf. I was going to make a large chart of numbers, but they all depend on your driving style and thus don't really fit all conditions or ways you may drive. Maybe the gear oil has never been changed in the life of vehicle? You will see a benefit, especially if it has over 10k miles. Want to experiment and go for a bigger benefit? You can try other gear oils that have a lower viscosity or better chemistry than the default Nissan uses, but just keep in mind that there is some inherit risk doing this. I would suggest reading over this whole topic and not just the end here to learn about the risk or using gear oil that is *too* thin.

TLDR; :mrgreen:
If your driving style is constantly keeping the motor above 140F (60C), then a gear oil change might benefit you. If your driving style is always keeping the motor at 190F (87C), then you probably won't notice much of a benefit to the gear oil change. The variables are too complex to say that a gear oil change equals instant range increase, but it won't hurt to try.
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goldbrick
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Re: Reduction Gear Oil Change - Benefits for Range

Tue Jul 27, 2021 1:22 pm

Nice write-up and thanks for sharing all your hard-earned learning.

One question I didn't see answered is what, if any, benefit do you see using a ULV oil when driving the car in cold weather?

DougWantsALeaf
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Re: Reduction Gear Oil Change - Benefits for Range

Tue Jul 27, 2021 1:26 pm

Fantastic research. Thank you

I will check the temp on my next highway journey.

I am keen to try the ULV if hitting the 140F barrier.
2019 S Plus (93.86% SOH) & 2019 SV Plus (93.35% SOH) Both Silver
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knightmb
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Re: Reduction Gear Oil Change - Benefits for Range

Wed Jul 28, 2021 5:18 pm

goldbrick wrote:
Tue Jul 27, 2021 1:22 pm
Nice write-up and thanks for sharing all your hard-earned learning.

One question I didn't see answered is what, if any, benefit do you see using a ULV oil when driving the car in cold weather?
Unfortunately, I won't know until it gets cold. I started my data gathering in Spring of this year and until winter arrives, I don't know what benefit there will be. The science in me says there will be a little, tiny, better range because less energy is needed to warm up the gear oil to it's optimal temperature, but since the energy vampire is the cooling system, if it is cold outside, it may not make much of a difference. I could be wrong; until I started taking measurements to compare the two.

I can say for certain, both the Gen 1 and Gen 2 Leaf basically behave the same, in regards to the cooling system. It takes a bit more to warm up the Gen 1 Leaf motor due to the 80kW power limit unlike mine where I can send 160kW into the motor and hit over 150F in a single run. :lol:

This winter, I will have a Gen 1 (2015) Leaf running ULV and I'll probably switch mine Gen 2 (wow, I'm the expert at changing my gear oil now) back to the Nissan Matic S after I do some measurements to see what the cold does to it.
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