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Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 10:43 am
by Goodbar
goldbrick wrote: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.

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 11:47 am
by LeftieBiker
estomax wrote:
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.
The Prius, probably because it doesn't have the usual transmission, has a separate differential that uses synthetic gear oil, not ATF.

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 11:51 am
by BrockWI
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?

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 1:03 pm
by goldbrick
Goodbar wrote:
goldbrick wrote: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.

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 1:14 pm
by LeftieBiker
Time marches on, and we fall behind...

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 1:34 pm
by Goodbar
goldbrick wrote:
Goodbar wrote:
goldbrick wrote: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.

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 1:59 pm
by goldbrick
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.

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 4:40 pm
by LeftieBiker
goldbrick wrote: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...

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 4:59 pm
by Nubo
BrockWI wrote: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.

Re: How To: Reduction Gear Oil Change

Posted: Thu Jun 06, 2019 7:16 pm
by Goodbar
goldbrick wrote: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 ... Manual.pdf

The 1994 Chevy Cavalier has a single transaxle fluid (p. 198):
https://my.chevrolet.com/content/dam/gm ... 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- ... -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.