How To: Reduction Gear Oil Change

[HRTKD]

@HRTKD - the Valvoline ULV ATF? Valvoline makes regular ATF too..

I'm not sure. They just called it Valvoline ATF, so I would assume it's the regular. But the dealership treated as an equivalent to Matic S. Doesn't mean it is equivalent, just that they treated it that way.

[knightmb]

https://www.valvoline.com/our-products/ ... oducts/ulv
viscosity of 4.45cSt @ 100c! i would assume lower is better for efficiency. anyone try it out yet?

I read up on what I used before and it's very close (even made by the same company), so it seems I was already running this in my 2013 Leaf and it ran great. I checked on the Redline D6, but what I was using before was already a lower viscosity than the Redline D6, and this one mentioned is even better! So yeah, if I can find this anywhere, this is what I'm going to put in my 2020 Leaf and see how it runs (or doesn't)

[edit] Had to order it online, can't find it in any nearby auto stores...

Will update this topic when I have more info.

[voltamps]

All would be fine in the Nissan Leaf, except the long term gear teeth and bearing wear in our reduction gearbox could be reduced a few thousand miles if you go to the thinnest in the group, the ULV stuff:

Redline D6 ATF: kv100 6.3
Amsoil Signature Series Fuel Efficient ATF: kv100 6.3
Valvoline MaxLife™ Multi-Vehicle ATF full synthetic: kv100 5.9
Mobil 1 Synthetic LV ATF HP ATF: kv100 5.7
Idemitsu Nissan Matic S: kv100 5.2
Valvoline ULV ATF full synthetic: kv100 4.5

Yes lower viscosity does mean more EV range. That would work.

Durability is a concern with the ULV fluids though.

[knightmb]

Durability is a concern with the ULV fluids though.

If it was shifting gears or using the fluid to actually drive the vehicle, I might have concerns. I would imagine that Valvoline wouldn't be selling it though if it was going to tear up expensive truck transmissions that handle forces triple what the Leaf would put on it, so I have confidence that it will work fine. I'm not so much concerned about the gears as I am the seals. From what I did some research on it shouldn't cause any leaks as even though the viscosity is lower, it's not physically smaller liquid that will seep through anything. That was more of my main concern.

[voltamps]

Durability is a concern with the ULV fluids though.

If it was shifting gears or using the fluid to actually drive the vehicle, I might have concerns. I would imagine that Valvoline wouldn't be selling it though if it was going to tear up expensive truck transmissions that handle forces triple what the Leaf would put on it, so I have confidence that it will work fine. I'm not so much concerned about the gears as I am the seals. From what I did some research on it shouldn't cause any leaks as even though the viscosity is lower, it's not physically smaller liquid that will seep through anything. That was more of my main concern.

You'll likely be OK with the low viscosity fluid. At least, "OK" in the sense that durability won't go down that much. Especially if you don't live in a hot climate, it'd be fine going a bit thinner than Matic S kv100 5.2
..............Although, it's not the forces inside, as you mentioned, it's the pressure (force per bearing face area). We engineers can get lower pressure (the 10-speed truck tranny example you cited) simply by giving it wider bearings, which those truck trannys have.

I doubt the ULV fluid is so thin that boundary tribofilm friction in the gear contact area exceeds the hyrodynamic viscosity effects. There is a crossover point when the viscosity drag reduction from thin oil is actually overwhelmed by increased gear teeth face contact (boundary) tribofilm friction. So you shouldn't go too thin. Where that point is, is probably only known to a couple of Nissan engineers. ..........

In other words, the thinness should result in higher EV range by a small amount. I think you could gain a half mile of range compared to using the Nissan Matic S spec chosen fluid with kv100 5.2 cSt.

seals: No problem since the seals are silicone rubber & don't react to squat.

[knightmb]

I doubt the ULV fluid is so thin that boundary tribofilm friction in the gear contact area exceeds the hyrodynamic viscosity effects. There is a crossover point when the viscosity drag reduction from thin oil is actually overwhelmed by increased gear teeth face contact (boundary) tribofilm friction. So you shouldn't go too thin. Where that point is, is probably only known to a couple of Nissan engineers. ..........

As you said, there is a limit somewhere, Nissan probably knows. I don't think the ULV fluid will get close to it since it won't be operating in a hot gear box. Sure, it might get hot outside and even some internal heat is bound to build up, but I would suspect no where near what a ICE engine operates at temperature wise since the fluid won't be compressed and heat won't be transferred from the firing of the cylinders inside. I could be wrong, but I will check it periodically to see if anything seems off (lots of metal build up on the magnets for example) or just weird noises that it wasn't producing before.

[voltamps]

Sure, it might get hot outside and even some internal heat is bound to build up,

Nissan engineers have specified kv100 5.2 oil to provide a sufficient viscosity margin to avoid gearbox thermal runaway, as well as basic long term acceptable wear rates. I wouldn't go lower than 5.2 myself, but it's still probably within the safety margin to go to 4.5, sure, why not. For all I know, Valvoline has more anti-wear chemistry in this ULV thin stuff to protect wear, similar to the way GL-5 differential oil has plenty of chemicals in the base oil to survive hypoid gear torture.

Thermal runaway is a cascading failure condition where a gearbox oil is too thin, which creates too much contact friction, which thins it out some more, which causes more friction, a death spiral. ( It happens in racing sometimes when, in their zeal to have low-drag oil, they get too thin & it fails.)

[goldbrick]

Personally - and this is just MHO - if I ever change my gear oil I'll just use the OEM stuff. It's not a big amount of $$ for something that I'll do once or never during the life of the car and I don't have to worry about using something that won't work. The risk vs reward ratio just doesn't support anything else for me. That said, my Leaf is racking up about 8k miles a year so I doubt I'll ever change the oil at all.

[voltamps]

Personally - and this is just MHO - if I ever change my gear oil I'll just use the OEM stuff.

I do admire the "Hyper-Rangers", like hypermilers in the hybrid/ICE world, that want to use a thinner Valvoline ULV ATF fluid to get a bit more Range. Enthusiasts! They blaze the trail. .... I wouldn't chance the wear rates, but it'll probably get more efficiency & Range out of a Leaf!

If I went "ULV" thin, I'd order the https://www.ravenol.de/en/product-range ... ulv-fluid/ from Blauparts.com because Ravenol uses PAO/ester base oils & has a reputation for exceeding performance specs.

Nissan Matic S fluid, from the dealership or Amazon ( https://www.amazon.com/Idemitsu-3004010 ... B08CRYPB74 ), would likely give the most Range out of a Leaf with the assurance of low-enough wear rates. ...Cuz it's thinner than almost anything else for efficiency. I very much doubt Redline D6 or similar thicker fluids have better efficiency, since viscosity drag dominates as the gears fling it around (shears it) inside the gearbox, although Redline or Amsoil would have better longevity.

I went with an all-PAO formula (Amsoil), changed the original fluid out earlier to get break-in metals out, and I expect it can now easily go 200k miles. If using Matic S, I'd change every 60k or so, still plenty good, no problem.

[knightmb]

I agree that the stock ATF that Nissan uses will work just fine and why spend more? Well, this is the one and only time I expect to change it on my EV, mainly to get out the little metal pieces that have built up since the vehicle was new. But...in my old 2013, when I did a gear oil change it in, the difference was a real-world noticeable with increased range, quieter gearbox, etc. A 0.2 miles / kilowatt hour increase on my old 2013 was like adding an additional +4 miles of range. Yeah, it's a small amount, but might be the difference between making it to the next QC or not when I was driving it. If I can get the same 0.2 miles / kilowatt hour increase on my 2020, that works out to an additional +12 miles of range, maybe.
Sure, seems kind of like "so......what's the point" but it is a permanent increase, not temporary. It's just a matter of trying to tweak the vehicle to squeeze every last bit of range out of it and it doesn't cost much to do it, nor difficult (now that I've already done it once, doing on another vehicle is easier). That is the way I am approaching this. I am curious if the gear box ever reaches 100 C inside to produce the temperatures needed to make the oil thin enough to reach the rated viscosity numbers. My guess is that it probably doesn't, but I haven't stuck a temperature prob in one after a long drive to find out (hmm... maybe another future project )