Reduction Gear Oil Change - Benefits for Range

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knightmb said:
More interesting data... charging via L2 raises the temperature of the coolant, gear oil, everything connected by 10F per hour when the outside ambient temperature is 75F. This is on a 2020 Leaf, not sure how it would equate to the earlier Gen 1 version(s), but still data non the less.

Interesting--the gear oil must be absorbing heat through the motor and gearcase metal as the onboard charger adds heat to the coolant system. Given this observation, the next question is how much heat is generated in the gearcase oil from friction and how much is added from motor and inverter electrical losses while driving.
 
It took all day, but I finally figured out the temperature needed to activate the radiator fans while in drive mode. I haven't been able to make this happen while charging because I just can't get the coolant hot enough, *safety*. :lol:

The coolant has to be 140F to activate the fans in "low" mode, which consumes about 200 watts per fan (400 watts total). In high mode, each fan consumes about 300 watts per fan (600 watts total). I don't know what temperature makes the fan(s) kick into high because getting the coolant to 140F is hard enough and a long wait. I only know that high mode exist because I can heat the sensor directly to make it kick into high mode, but I don't know what temperature that is exactly because the coolant is already being cooled by the fans and thus fighting the higher temperature. Maybe someone with some in-depth Nissan cooling system knowledge can share. :D

But...the temperature of the gear oil has no effect on this. For example, I can cruise down the Internet state at +70 MPH and the gear oil is showing +160F, but the coolant is only showing +100F, so the fans never switch on. I've also found that the water pump has a high and low mode, but I haven't been able to measure the power usage yet. It kicks into high at 140F also (coolant temperature, not gear oil temperature).

I believe there are some systems that will kick the cooling system into high when the motor/inverter/etc get hot enough without waiting for the coolant to reach the temperature. I was able to see this for myself by doing full power 0 to 100 MPH test runs and watch the radiator fans come on well before the coolant temperature was hot enough by putting a camera into motor area and recording what happens.

The variables for the Leaf cooling system can get pretty complex, but I think I have enough data and measurements that I should be able to sort out any changes before and after my reduction gear oil change.

So far, normal (under 55 MPH) driving hangs the gear oil temperature around 140-142F with no radiator fans running (no AC) and with the AC running, which make the radiator fans run, keeps the gear oil temperature around 128-133F. High speed driving (+70 MPH) will range the gear oil temperature from 160-172F depending on how aggressive and/or fast you drive. AC has no effect on it, on or off at that speed. The coolant temperature in all those circumstances always keeps below 100F. The only way I've been able to get it higher than 100F is to either let it charge on an L2 for hours or do I like I did today and put a heat-gun in the motor area and leave it running on high for a long time while aimed at the motor block while the water pump runs (either while charging or in drive mode)

Another week of data collecting and I'll be ready to make the swap back to Nissan OEM gear oil. :mrgreen:
 
That's some great data captures. And your temperature finding is exactly inline with the tables in the FSM; the EVC section has a cooling fan control section with a table of temperature and vehicle speed, also tables to include factors for the HVAC. Starts on EVC page 43 in the 2012 manual.
 
Today is the day (June 12, 2021), did the reduction gear oil swap to Nissan Matic S.
First gear oil change to ULV @ 12,478 Miles, today the change is happening @ 17,330 miles, so a good 4,852 miles on the ULV. I captured another sample for Blackstone Labs Oil Analysis, will be sending that in the mail today. I will begin monitoring temperatures and efficiency for the rest of month to offer up a comparison when I am done. The magnetic plugs were quite clean once I let the oil drip off for about 15 minutes on a paper towel, the pictures are how they looked before I even wiped them down. I see some metal shards, but nothing like the first change. The old ULV oil came out quite bright red and clear.
Will be interesting to see if the default Nissan Matic S makes any difference. :shock:

Nissan Matic S
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Oil from ULV for Lab Analysis
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Magnetic Plugs
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First Gear Oil Change for Comparison
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So very surprising first temperature readings today.

Before, with the ULV, driving around under 55 MPH keeps the gear oil temperature around 140-142F with no radiator fans running (no AC) and with the AC running, which make the radiator fans run, keeps the gear oil temperature around 128-133F. The coolant temperature never gets over 100F, actually runs about 10 degrees above outside ambient air temperature when the AC is on, thus keeping the radiator fans running. So if it is 80F outside, the coolant temperature would run about 90F for example.

Today was cloudy, outside temperature about 78F, so a good day to run around town and get some temperature readings. At first everything appeared to be in line with the ULV and honestly I wasn't really expecting the temperature readings to be different at all. I was running the AC as usual, the car was comfortable inside, and I would occasional glance at the temperature probe readings. Then while at a stop light I glance down and say out loud WTF? The gear oil temperature has broken +152F and the coolant temperature is +96F instead of somewhere around 88F which is normal for this time of day and temperature. I continue to drive for a few more minutes before pulling over to a restaurant parking lot and just watching the probe for a minute. The temperature does start to tick back down but as it does, the coolant temperature continues to climb. Finally, the coolant temperature goes past 100F, a first, I've never seen it do that before *with* the AC still running. While I am sitting there, I hear the radiator fans kick into high mode, what?! As the temperature is being pulled down by the radiator fans, the coolant temperature continues to increase past 100F. So I continue to drive around for a few more miles on my way home, but the gear temperature stays hot and the coolant temperature stays higher than I've ever seen it before in this set of conditions. This was the first drive right after a fresh gear oil change and the gear box has exactly 1.5 qt in it, so I know I didn't under-fill or over-fill the box. The gears are nice and quiet, no odd sounds from the gear box.

I was not expecting this radical difference in temperature readings before this change, a lot of extra heat is generated now. This will require further study and hopefully some future efficiency readings will show if this is having an effect on range or not. To be continued...

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This is the first longer trip I've had the time to take on the Nissan Matic S today. I wanted to try my +25 mile route to see what kind of temperatures driving at +70 MPH generates in the new gear oil. I usually get around 3.9 miles/kWh on this route with the gear oil maintaining a temperature of around 160F. Today, running the same tire pressure (42 PSI) and slightly cooler air temperature (82F vs 85F on the other days with the ULV), gear oil temperature was staying well into the +183F range with the efficiency getting around 3.6 miles/kWh for the total trip. Other than the gear oil temperature, which I couldn't measure before, it's pretty close to identical to the original gear oil for efficiency. I'll need more time to gather data, but so far, without a doubt, gear oil temperatures are operating +20F hotter than with the ULV. There is certainly more "resistance" in the system to be generating more heat, but how much it affects range, I'll need another couple of weeks of data to really see the difference this is making in the grand scheme of things for power usage.

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knightmb said:
... I usually get around 3.9 miles/kWh on this route with the gear oil maintaining a temperature of around 160F. Today, running the same tire pressure (42 PSI) and slightly cooler air temperature (82F vs 85F on the other days with the ULV), gear oil temperature was staying well into the +183F range with the efficiency getting around 3.6 miles/kWh for the total trip....

Your efficiency numbers continue to show a consistent difference between the two oils, and the temperature difference would seem to corroborate. I would never have expected the ATF was getting that hot. If the oil analysis results are good I may be convinced to try the ULV stuff.
 
The benefit is small for total range, because even a +0.3 bump in efficiency only equates to maybe 18 extra miles for the 62 kWh pack or less than 12 miles for the 40 kWh should you run them from 100% to dead battery. On shorter trips, it would be hard to actually see the difference other than better efficiency readings if you compare the before and after.

But... the extra heat being generated got my attention. I think that the extra friction of the gear oil means the motor has to work slightly harder and thus that extra heat is "vented" to the batteries and cooling system. Since the batteries are air cooled, I wonder if this could help keep them to stay just a little bit cooler?

When I get the Blackstone Lab report back, I'll have a better idea if the ULV is damaging the gears. It might not be worth the trade-off to save some extra miles and heat generation if it comes at a cost to the gears and causing future problems. But... if the report shows nothing abnormal, I'm going to switch back to the ULV immediately once I'm done collecting data. Who wouldn't want a small, but permanent boost to range and performance? :lol:
 
Nubo said:
knightmb said:
... I usually get around 3.9 miles/kWh on this route with the gear oil maintaining a temperature of around 160F. Today, running the same tire pressure (42 PSI) and slightly cooler air temperature (82F vs 85F on the other days with the ULV), gear oil temperature was staying well into the +183F range with the efficiency getting around 3.6 miles/kWh for the total trip....

Your efficiency numbers continue to show a consistent difference between the two oils, and the temperature difference would seem to corroborate. I would never have expected the ATF was getting that hot. If the oil analysis results are good I may be convinced to try the ULV stuff.

Interesting physics happening here. @knightmb 's magnets looked clean after 5k miles on Valvoline ULV, that's for sure.

I'd guess the Valvoline ULV should have very near the same gear & bearing wear rates as the factory-standard Nissan Matic S thicker stuff, since the operating (hiway running) hot viscosity actually ends up being about 8 cSt for both. This is because the Valvoline ULV is at about 160F (~70C) & Matic S runs at around 180F (~80C).

........The cooler ULV is 8 cSt there, same for the warmer Matic S, meaning the gears & bearings experience the same viscous friction (shear force or torque) losses when hottest, and that is the same heat transfer flux conducted thru the metal casing. Any Range Gains should be only during the time it takes to heat them up to their top stabilized max temp, certainly significant since the Valv ULV starts out thinner from cold. Valv ULV is thinner when cool or cold, yet still looks to be plenty thick enough under those conditions to not produce excessive wear rates when cool.

Note in the graph and table below that they both stabilize at around the same viscosity, Valv ULV @70C vs. MaticS @80C, as measured by @knightmb . Heat generated in the gears ends up, after a while, being the same between the 2 fluids, as the water-glycol coolant loop draws off the casing's heat at about the same rate in either example (ULV vs. MaticS).

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In @estomax 's case, using high-visc kv100 15 cSt GL-5 gear oil instead of thinner ATF, you would think temperatures get pretty hot inside the gearbox & aluminum housing, compared to @knightmb 's situation (& other Matic S Leafs). ... estomax reported barely-noticeable decreases in Range using the thick oil, so could be the temperatures inside just climb up enough to lower the impact of a thicker fluild to some extent there too.

@knightmb might be uncovering the reason why Ford is now using thin ULV ATF in their rear MachE gears. I'll bet the engineers there are finding benefits for Range & power reaching the ground during warm-up phases, and cooler running, without much higher wear rates.
Ford went to 0w-20 (thinner engine oil) over a decade ago since they probably noticed very little loss in long-term durability while getting lower overall friction (gas savings) benefits, from customer & EPA CAFE pressures. An EV has Range-increase market pressure!

Key: Look for the new Ariya's owner's manual to spec thinner ATF fluid like Ford is doing, as it's got to be the future trend.
 
DougWantsALeaf said:
Do you feel the .3 benefit is still accurate?

It seems that way, but I want to collect more data. It is a lot hotter now than it was a few months ago, so I have to run my test either in the early morning or late evening to get matching temperatures. The vehicle doesn't feel slower or any lose of performance. Speaking of anecdotally, it seems the gear whine is louder now. That is all subjective of course, might just be me. That's why I like to stick with the temperature and efficiency readings.

I have a feeling that the first gear oil change (regardless if you use Nissan default or not) is probably the greatest benefit.
This morning, running the same tire pressure (42 PSI) and cooler air temperature, gear oil temperature was staying a little lower into the +180F range with the efficiency getting around 3.7 miles/kWh for the total trip. The original factory fill never got that, but I got it using the same Nissan Matic S this morning, so that was nice to see something different for once. :lol:
Will it hold out for the rest of the month, don't know.

It might be more accurate to say the first gear oil change after gear break in will give you a benefit and using thinner stuff just increases the benefit further.
 
I'm starting to re-think my decision to use the slightly-thicker Amsoil SS ATF fluid over the standard, thinner, Matic S in my own '20 Leaf.

As @knightmb 's measurements show, the hot peak stabilized temperature for Matic S is about 180F (under those conditions, a warm day, high-speed driving). If Amsoil SS does NOT deliver significantly lower boundary friction (non-viscous friction) , then Amsoil SS ATF in there should peak out at 190F in those same conditions. (There could be a lower boundary-friction traction coefficient, not sure how much really, in Amsoil SS, being a GroupIV syn with maybe some esters(?). Ravenol claimed those base oils lower traction coefficient anway.)

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As a side note, the 180F that knightmb gets on a Leaf was the very same peak temperature many of us would get (as read off the OBDII ELM327 thingie) on the Ford C-Max Hybrid, a fixed-gear planetary arrangement, not too different from a Leaf since it's all fixed, with no clutches, etc., no shifting mechanisms. And it used a MaticS-like Mercon LV. This tells me the engineers design the heat flow, in and out, to get it to stabilize at 180F on a hot day, allowing the use of a similar fluid on different makes & types of vehicles, a C-Max vs. Leaf.
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Another way to put this: The conduction-cooling of the gearbox housing looks to be approximately constant, from the temperature measurements, explaining two things:
1. Thicker Matic S is around 20F hotter at peak than Valv ULV.
2. This gearbox, with heat flow in & out, is designed to settle into ~8 cSt.
(Temperature only stabilizes, steady state, when Heat In = Heat Out.)

As for the cooling system on a Leaf, it just circulates coolant around the electronics & motor, correct?
That would mean the gearbox is cooled through aluminum housing conduction (with some air cooling to the exterior). The radiator can likely handle some extra gearbox heat via the normal coolant-radiator-fan pathway. Maybe I shouldn't think an extra 5 or 10 deg F from Amsoil SS (same applies to Redline D6, btw) would be any problem.
 
voltamps said:
As for the cooling system on a Leaf, it just circulates coolant around the electronics & motor, correct?
That would mean the gearbox is cooled through aluminum housing conduction (with some air cooling to the exterior). The radiator can likely handle some extra gearbox heat via the normal coolant-radiator-fan pathway. Maybe I shouldn't think an extra 5 or 10 deg F from Amsoil SS (same applies to Redline D6, btw) would be any problem.
As far as I can tell, the coolant lines come in right next to the gear box. So while maybe not directly circulating around it, sure is dang close. :lol:

What I am seeing (it's only been a few days now) is that the gear oil temperature stays between 20F-25F hotter. That's just normal driving, not being an aggressive driver or playing stop-light champion. It also seems to keep the coolant temperature about 20F hotter as well. Not enough to kick on radiator fans as it appears the air flow can remove enough heat quick enough, but I guess that just means the coolant pump runs on high mode instead of low mode? For example, if the outside temperature was 80F and you just drive around town (speeds under 55 mph) then with the ULV, the coolant temperature stays between 88F and 90F. The gear oil temperature will stay between 130F and 140F. Under the same conditions now, the Nissan Matic S is keeping the gear oil temperature between 150F to 155F and coolant temperature between 100F and 104F. Range efficiency *seems* so far to have dropped by about 0.2. I want at least the rest of this month to record trip data to see if that goes away and equals out, or gets better, worse, etc. Running the AC at the same time certainly adds more heat to the system and quickly keeps the AC system running on high fan mode from what I've noticed compared to before. It also seems like running the AC doesn't cool the gear oil down further during normal driving like I was seeing with the ULV. The gear oil running cooler might be saving a little power in the cooling system and performance of the electric motor if it is running say 20F cooler than usual. It's a small, but interesting bump in efficiency.

The temperature difference is interesting and running a little hotter probably isn't hurting any engine components. Being that the gear box sits in front of the air flow to the batteries, I do wonder if having less heat carried away by the air and blown across the main battery offers any benefit. :cool:
 
knightmb said:
The temperature difference is interesting and running a little hotter probably isn't hurting any engine components.
Since you're noticing an increase in Coolant Temperature, not just gearbox probe temperature, I wanted a way to check the very important Motor+Inverter "box" housing temperature, just to be sure my slightly-more-viscous ATF (Amsoil SS) I'm running isn't creating too much extra gearbox heat which conducts across the aluminum main housing to heat up the vital electronics & motor.
I did order one of those cheap infrared thermometers on Amazon to scan the metal housing somewhere to see how the whole thing is packing heat. Even if it isn't used here, I've always wanted one for other purposes. Good cheap tool. You can try to use them to figure out if somebody's forehead is too hot (covid19, other fever causes, etc.).

I just loaded LeafSpy Pro to see if I can get Motor+Inverter electronics temperature the Leaf monitors for us internally. After some hunting, turns out Page 4 of LeafSpy Pro has it. Some notes on https://mynissanleaf.com/viewtopic.php?t=23353 for the iPhone version, but my Android version looked a little different, circled in red:

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voltamps said:
I just loaded LeafSpy Pro to see if I can get Motor+Inverter electronics temperature the Leaf monitors for us internally. After some hunting, turns out Page 4 of LeafSpy Pro has it. Some notes on https://mynissanleaf.com/viewtopic.php?t=23353 for the iPhone version, but my Android version looked a little different, circled in red:
I was so excited when I read that. I was about to go bug the guys in the LeafSpy forum about additional temperature sensors and where to find them. So I did a real quick test on the Interstate because that is the quickest way to heat up everything. The temperature in LeafSpy leads the Gear Oil temperature almost perfectly. For example, I start accelerating and hold it at a speed (say +70 MPH) to get the motor (I guess that is the sensor, is must be!) in LeafSpy to raise up quickly to 140F for example. I can watch the Gear Oil temperature slowly catch up and match it perfectly on the Probes. Now, I exit the Interstate and just go sit in the parking lot for a few minutes, I can watch the temperature of the "motor" cool down quickly to say 120F. The gear oil temperature will follow, but again, slowly, takes a lot longer for the gear oil to cool down than for the motor to cool down. My guess is the motor + electronics are getting the benefits of the coolant circulating and the gear oil just gets the passive cooling by being physical connected to the whole thing. Dang, I wish I had found that in LeafSpy last month, now I almost want start over and collect data from (3) different temperature readings. :lol:

Will this data collection never end! :shock:
 
knightmb said:
I can watch the Gear Oil temperature slowly catch up and match it perfectly on the Probes.
That would agree with everything we think we know so far. I think we're on the right track in understanding all this. .... Gearbox gets cooled some by aluminum housing heat conduction (little bit of air cooling too), sort of indirectly from motor+inverter cooling radiator loops.

For the dynamics, I'm interested in something the Nissan gearbox engineers probably target & know about: The viscosity seems to settle out (equilibrium), within a certain reasonable range of ATF fluids, yet, as knightmb found, thicker ATF fluids create higher steady-state peak temperature affecting the entire metal "box" under the hood.

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Note gearbox efficiency is better the lower the viscosity, and gearbox temperature is governed by power (heat) wasted in there, integrated with a gain as a function of the specific heat of the fluid plus metal.

That shows us it sort of settles into a stable viscosity state. At least as long as the coolant radiator loop is able to remove enough heat, which is certainly does. ..... ((( "Transfer Function" engineer geeks out there may consider this a basic 1st order Laplacian lag function with a variable time constant (tau) and disturbances, looking a bit similar to my old job modelling aircraft landing under wind gust disturbances. )))

I'd say, estomax might want to think about removing the super-thick GL-5 gear oil in there after all, in light of knightmb's discovering slightly elevated temperatures with a mere 20% shift in ATF viscosities installed. Or at least monitor the LeafSpy temperature (motor-inverter one). Of course, if it gets really bad, the Leaf's own computer will light up a cockpit warning light, so there is that !! No warning light, no problem, .... although .... the cooler the underhood electronics & motor get, the longer that stuff lasts.

Like Nubo, I might consider trying the Valvoline ULV if I can get a cooler running aluminim chunk under the hood. Cooler fights ageing, less warrany claims for Nissan, and cooler means the ULV really functions at around the same ultimate visc as Matic S or Amsoil SS anyway!

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I need to take a drive in the mountains near Denver, since it's hot as Hades here, and car-makers love "hot & high" for durability testing of new models, months away from showrooms. I could see an Ioniq5 or something nice like that, who knows, as I've seen new model C8 Corvettes barreling up the mountain (Mt. Evans 14k ft) in the past, for example, before it hit showrooms.
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knightmb said:
The temperature in LeafSpy leads the Gear Oil temperature almost perfectly. For example, I start accelerating and hold it at a speed (say +70 MPH) to get the motor (I guess that is the sensor, is must be!) in LeafSpy to raise up quickly to 140F for example.

I did a run here in Colorado & got a first useful look at the new LeafSpy Pro app I installed yesterday:

'20 Leaf SV 40kWH
Tires: 44 psi in the heat, not normally that high.
Air Temperature: 96F (unusually hot for us)
Elevation: 5,800', thin air makes radiators less effective.
Speed: 70 mph
Miles: Around 12 miles of hiway travel.
Starting Motor-Inverter Temperature (MIT): 122F hooked up to charger in the heat before leaving.
Ending MIT: 155F
ATF: Amsoil SS, which is 20% thicker than Nissan Matic S, 35% thicker than Valvoline ULV....

If knightmb's observations that thicker ATF pushes temperatures up some pans out, I may not want to stick with Amsoil SS (Redline is exactly as thick, so applies to the crowd who likes Redline D6 too.).

OK, it's a hot day, might just be that. 155F > 140F that knightmb got under cooler conditions, but seems like some difference anyway.
And, it's only one data point. I'll get some more. Headwinds are going to throw it off sometimes. The wind today was light, next time I need to note it. I can control the route, since it's one I take at least once a week.

knightmb said:
Will this data collection never end! :shock:
When my infrared thermometer arrives tomorrow, I could go nuts with that thing for a while.
 
For those into LeafSpy Pro, page 4, the Motor-Inverter Temperature next to that weird "gids" name,
... What's the highest temperature you can get to on that? I just did 155F on a hot day, 70mph cruising for 12 miles. Later I may switch to a lower visc ATF fluid & see if it nudges down some.
 
SageBrush, One transfers heat to the other, in time lags. I see this in 2 ways, just to whittle this down:
1. Thicker ATF appears to create enough extra heat to cause the electronics & motor to run hotter.
2. It's bad for the non-gearbox part of the big aluminum box to get extra heat. Hurts longevity of electronics, etc.

At least knightmb has proven, so far anyway, that Valvoline ULV creates cooler coolant temperatures, as measured by his probes.
Now I'm trying to figure out if my choice to go with a thicker (than Matic S) ATF fluid elevates temperature yet another notch.
The LeafSpy temperature sensor should tell us if we are running hotter than normal, & normal is defined as whatever Matic S gives us.

Cooler with Valvoline ULV would be nice, especially since it looks like it creates the same operational viscosity as warmer Matic S does. That should keep wear OK.

Range changes? Certainly lower visc during the warm-up phase uses less energy. Measured benefits appear to be more than just that.
 
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