How To: Reduction Gear Oil Change

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Nubo said:
Goodbar said:
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.
 
Goodbar said:
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 :)
 
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!
 
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...
 
powersurge said:
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).
 
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.
 
LeftieBiker said:
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.
 
Goodbar said:
LeftieBiker said:
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.
 
LeftieBiker said:
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.
 
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.
 
goldbrick said:
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.
We're not talking about standalone diffs. As estomax said, for a front-drive car, you have a transaxle with a single fluid that lubricates the transmission and differential because they are in the same case. Maybe there are some rare exceptions, but nearly every manual or automatic transaxle in production vehicles will have one fluid. For an automatic transaxle that means the differential portion is lubricated with ATF.
 
estomax said:
LeftieBiker said:
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.

The Prius, probably because it doesn't have the usual transmission, has a separate differential that uses synthetic gear oil, not ATF.
 
Correct me if I am wrong but the ATF D6 if fine to use in this gear box correct? It seems like a better grade that what was in there?
 
Goodbar said:
goldbrick said:
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.
We're not talking about standalone diffs. As estomax said, for a front-drive car, you have a transaxle with a single fluid that lubricates the transmission and differential because they are in the same case. Maybe there are some rare exceptions, but nearly every manual or automatic transaxle in production vehicles will have one fluid. For an automatic transaxle that means the differential portion is lubricated with ATF.

Well, I'll be....ATF D6 is new to me but I don't agree it is a 'rare exception' that that FWD cars use different oils for the transmission and differential. Every automatic transmission I've ever seen uses AT fluid (eg Dextron, Mercon, Type F, etc) for the transmission and gear oil for the differential. This is for front wheel drive (or 4WD) cars. As Leftie said, just because the trans and diff are in the same outer case doesn't mean that they share oils. In many cases, there is a separate fill plug (often just a hex-head bolt) that is used to check and/or top off the differential oil. The main transmission fluid is usually drained from a plug on the bottom. I don't know when ATF D6 came into being or what transmissions use it but as one example, any ZF built 'tiptronic' transmission as found on VWs, Audis, BMWs, etc, etc will use both ATF fluid for the transmission and gear oil for the differential. They are in the same 'case' but they do not mix.
 
goldbrick said:
Goodbar said:
goldbrick said:
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.
We're not talking about standalone diffs. As estomax said, for a front-drive car, you have a transaxle with a single fluid that lubricates the transmission and differential because they are in the same case. Maybe there are some rare exceptions, but nearly every manual or automatic transaxle in production vehicles will have one fluid. For an automatic transaxle that means the differential portion is lubricated with ATF.

Well, I'll be....ATF D6 is new to me but I don't agree it is a 'rare exception' that that FWD cars use different oils for the transmission and differential. Every automatic transmission I've ever seen uses AT fluid (eg Dextron, Mercon, Type F, etc) for the transmission and gear oil for the differential. This is for front wheel drive (or 4WD) cars. As Leftie said, just because the trans and diff are in the same outer case doesn't mean that they share oils. In many cases, there is a separate fill plug (often just a hex-head bolt) that is used to check and/or top off the differential oil. The main transmission fluid is usually drained from a plug on the bottom. I don't know when ATF D6 came into being or what transmissions use it but as one example, any ZF built 'tiptronic' transmission as found on VWs, Audis, BMWs, etc, etc will use both ATF fluid for the transmission and gear oil for the differential. They are in the same 'case' but they do not mix.
Can you specify a FWD model? I'm genuinely curious because I haven't come across one. (Admittedly, I'm a manual transmission guy and haven't owned any FWD automatics.) Are there any FWD BMWs?

AWD/4WD can be a different beast owing to a center diff or transfer case.
 
VW Passat (1998-2005). I'm sure there are many, many more.

I think Leftie nailed it though....after some googling it appears that all/most newer vehicles do indeed share AT fluid with the differential. I don't know when that tech was developed but the only car I have ever owned that was built less than 12 years ago is my 2017 Nissan Leaf.
 
goldbrick said:
VW Passat (1998-2005). I'm sure there are many, many more.

I think Leftie nailed it though....after some googling it appears that all/most newer vehicles do indeed share AT fluid with the differential. I don't know when that tech was developed but the only car I have ever owned that was built less than 12 years ago is my 2017 Nissan Leaf.

I assume that this is a design change to save costs, both in manufacturing and when servicing the vehicles. I only hope that the filter(s) are in the stream between the differential and the transmission...
 
BrockWI said:
Correct me if I am wrong but the ATF D6 if fine to use in this gear box correct? It seems like a better grade that what was in there?

Redline claims it is satisfies Nissan "Matic S" specs. So it should satisfy any warranty concerns. Seems like a high quality synthetic lube that is somewhat lighter, and should thus give some efficiency improvement. I put it in about a year ago.

Anecdotally, I have a floor fan in constant use that kept overheating its bushing-bearings. I tried various oils and they'd only last a couple of weeks. I finally used a few drops of the D6 and the fan has been going strong for nearly a year now.
 
goldbrick said:
VW Passat (1998-2005). I'm sure there are many, many more.

I think Leftie nailed it though....after some googling it appears that all/most newer vehicles do indeed share AT fluid with the differential. I don't know when that tech was developed but the only car I have ever owned that was built less than 12 years ago is my 2017 Nissan Leaf.
Interesting about the B5 Passat.

The 1986 Honda Accord auto transaxle just took ATF (pp. 3-5, though all the gory details are there if you want to peruse):
http://www.wedophones.com/Manuals/Honda/Honda%20Accord%201986%20-%201989%20Maint%20&%20Repair%20Manual.pdf

The 1994 Chevy Cavalier has a single transaxle fluid (p. 198):
https://my.chevrolet.com/content/dam/gmownercenter/gmna/dynamic/manuals/1994/chevrolet/cavalier/1994_chevrolet_cavalier_owners.pdf

The 1990 Toyota Camry has a separate drain/fill for the differential... But it takes ATF for both!
https://www.toyotanation.com/forum/102-camry-1st-2nd-gen-1983-1986-1987-1991/1158449-transaxle-differential-oil-change-info.html

This isn't new tech, it's what almost every FWD transverse-mounted (which is almost all of them) drivetrain has with an automatic. The B5 Passat is a bit different that most FWD cards in having a longitudinal drivetrain, presumably so that AWD could be offered.
 
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