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Re: How To: Reduction Gear Oil Change

Posted: Tue Jun 04, 2019 1:05 pm
by Goodbar
Nubo wrote:
Goodbar wrote:I checked the level per the maintenance schedule at 15k miles/2 years. I used a bunch of extensions so I didn't have to pull the belly pan.

This is what the plug looked like — should I be worried?!
https://i.imgur.com/geSVlNQ.jpg
Looks fairly normal. Manufacturing the gear teeth perfectly polished and mated to each other would be prohibitively expensive, so it's done inside the gearbox by the driver. Most of those metal particles are from the first few thousand miles of use.

But -- the effort it takes to get the fill plug out is not all that much more than draining and re-filling. I like the idea of getting the initial wear-metals out of the case.
Interesting. Doesn't cleaning the magnet get the initial (ferrous) wear metals out of the case? I'm OK with doing fluid changes on the early side, but 15k miles is too early for me. I zipped the plug out from the wheel well so I didn't have to remove the belly pan, so a fluid change would have been a much bigger project. Plus I don't have ATF on hand, yadda yadda.

Re: How To: Reduction Gear Oil Change

Posted: Tue Jun 04, 2019 8:48 pm
by Nubo
Goodbar wrote:Interesting. Doesn't cleaning the magnet get the initial (ferrous) wear metals out of the case? I'm OK with doing fluid changes on the early side, but 15k miles is too early for me. I zipped the plug out from the wheel well so I didn't have to remove the belly pan, so a fluid change would have been a much bigger project. Plus I don't have ATF on hand, yadda yadda.
The magnets will capture particles of a certain size. Smaller particles will stay in suspension. With a gearbox running a clear oil you can see fairly easily how "silvery" the oil is when you change it. It's a bit harder to see with ATF which turns dark in use, but if you shine a strong light you can still see it sparkle. As to whether these finer particles matter much, I don't know. Probably not, but it bugs me :)

Re: How To: Reduction Gear Oil Change

Posted: Wed Jun 05, 2019 8:43 am
by estomax
the sooner after 'break-in' you do this the more benefits you will realize through a slight increase in efficiency that several people have noted. But yeah, those particles on your plug are from the break-in of the gearbox, nothing really to worry about!

Re: How To: Reduction Gear Oil Change

Posted: Wed Jun 05, 2019 10:48 am
by powersurge
I am sorry, but there is no need to change transmission fluid "after break-in". There is no break-in period, as it is an electric motor, with no heat for wear.

As per Nissan, there is no need to change the fluid...... My feeling is to change just like ICE vehicles, at 30-40K miles. The Fluid does not sludge up, you just need to remove the contaminants...

Re: How To: Reduction Gear Oil Change

Posted: Wed Jun 05, 2019 11:33 am
by Goodbar
powersurge wrote:I am sorry, but there is no need to change transmission fluid "after break-in". There is no break-in period, as it is an electric motor, with no heat for wear.

As per Nissan, there is no need to change the fluid...... My feeling is to change just like ICE vehicles, at 30-40K miles. The Fluid does not sludge up, you just need to remove the contaminants...
Yup, that's where I've landed, too. I'll change it at 30k. Which is probably plenty early. Anecdote: I changed the factory ATF in a 2006 Prius at 155k miles. There's more going on with in the planetary gearset CVT than there is in the Leaf reduction gear and that car is still going strong with its new owners (friends) three years and 30k+ miles later.

As for break-in, I think that can apply generally to machined parts, not just ones that see a significant thermal cycle. With the larger ferrous bits caught by the magnet, I'm guessing there's little to no harm to the bearings. If there were, I'm guessing Nissan would have specified a replacement interval, as there is for coolant (125k or 15 years).

Re: How To: Reduction Gear Oil Change

Posted: Wed Jun 05, 2019 11:41 am
by LeftieBiker
Differential assemblies are not automatic transmissions. They are machined to somewhat lower tolerances and they do throw shavings during break-in. It is true that you can get away with just normal service intervals (again because of those more lenient tolerances) but few car owners want to drive around with the oil in anything (maybe excepting the paint) filled with metal flakes.

Re: How To: Reduction Gear Oil Change

Posted: Wed Jun 05, 2019 12:10 pm
by Goodbar
LeftieBiker wrote:Differential assemblies are not automatic transmissions. They are machined to somewhat lower tolerances and they do throw shavings during break-in. It is true that you can get away with just normal service intervals (again because of those more lenient tolerances) but few car owners want to drive around with the oil in anything (maybe excepting the paint) filled with metal flakes.
In a front-drive ICE car the differential is in the same case as the transmission.

Re: How To: Reduction Gear Oil Change

Posted: Wed Jun 05, 2019 3:21 pm
by LeftieBiker
Goodbar wrote:
LeftieBiker wrote:Differential assemblies are not automatic transmissions. They are machined to somewhat lower tolerances and they do throw shavings during break-in. It is true that you can get away with just normal service intervals (again because of those more lenient tolerances) but few car owners want to drive around with the oil in anything (maybe excepting the paint) filled with metal flakes.
In a front-drive ICE car the differential is in the same case as the transmission.
It is usually provided with a separate reservoir of lubricating fluid, as I understand it.

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 9:18 am
by estomax
LeftieBiker wrote: It is usually provided with a separate reservoir of lubricating fluid, as I understand it.
Nope, it is called the transaxle and all the ones i've seen use a single fluid/compartment. Whether manual or automatic.

Still, break-in applies to any machined gears that mesh and you can say changing the fluid is only for those of us that are anal, Nissan does not require you to do it. It certainly wont hurt though, and it will provide a peace of mind and maybe better efficiency.

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 10:33 am
by goldbrick
I've never seen a differential that specifies AT fluid for lubrication. It's usually something like 75W90 GL-4 or GL-5 gear oil, which is certainly not what you would put into any automatic transmission that I have ever heard of.