Forums/Z31P/z31-repairs-forums driveline/synthetic or conventional
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pokeyquick: (2016-06-21 13:18:14)
Wanted to know if Mobil1 Synthetic Gear Lubricant LS 75W-90 is ok for the FS5W71C tranny?
Reds89: (2016-06-22 13:34:50)
You must use a GL-4 oil. I highly recommend Redline Synthetic http://www.redlineoil.com/product.aspx?pid=46&pcid=7
You can get it shipped to you by Amazon or Summit. I think I used 4 or 5 quarts for my trans. Makes a big difference in the smoothness of shifting and is not as sticky in cold weather.
Pace: (2016-06-22 13:47:51)
Or save some money and get the same MT90 fluid from ASCO. [archived image: wink.png] http://store.acadianasportscars.com/asco503043p
I bought a 3-pack from them last month. Used two quarts in my T5 and have one left for the differential. Your 71C should use the same amount.
frostvectron: (2016-06-22 17:38:02)
Ummm. I remember reading a pretty old post about GL4 vs GL5 oils. There was a recommendation for Motul Gear 300, which I am currently using… but now I am googling it and a few results pop up saying the Motul Gear 300 is GL4/GL5 (i.e. not good for GL4-only applications)… did something change?
Edit: This thread: https://z31performance.com/forum/z31…-can-be-a-pain
Edit #2: More digging… from the s2000 world:
http://www.s2ki.com/s2000/topic/9291…y-experiences/
http://www.s2ki.com/s2000/topic/9482…-differential/
maxBirdy: (2016-06-23 07:11:53)
Or save some money and get the same MT90 fluid from ASCO. [archived image: wink.png] http://store.acadianasportscars.com/asco503043p
I bought a 3-pack from them last month. Used two quarts in my T5 and have one left for the differential. Your 71C should use the same amount.
You need 3 qts for the 71c and youre supposed to use ATF in the T5.
pokeyquick: (2016-06-23 10:20:20)
Thank you all !!!!!!
Augustus Maximus: (2016-06-23 14:16:43)
If it takes more than three something is very wrong
Or save some money and get the same MT90 fluid from ASCO. [archived image: wink.png] http://store.acadianasportscars.com/asco503043p
I bought a 3-pack from them last month. Used two quarts in my T5 and have one left for the differential. Your 71C should use the same amount.
As much as I love synthetic I'd never use it in my CLSD diff.
Pace: (2016-06-23 22:40:12)
You need 3 qts for the 71c and youre supposed to use ATF in the T5.
Interesting… Amsoil's spec sheet shows 4 pints for the 71C in the Z31. I don't have one to compare to, so my mistake if incorrect. A 3-pack is still sufficient for the transmission alone then.
However, ATF is recommended for the WC T5, not the Non-WC T5 that came in our Z31s. WC T5s came with fiber-lined brass synchros and require ATF to keep the lining intact. Non-WC T5s have standard brass synchros and need a GL-4 type fluid. Run ATF in a Z31's T5 and you'll find that first and second gear synchros can develop a nasty whine.
There's a sticky on this linked above. I would recommend checking it out.
As much as I love synthetic I'd never use it in my CLSD diff.
Currently running an open diff. [archived image: wink.png]
With that said, I've used synthetic in other CLSDs before. Most brands recommend a limited slip additive to keep things quiet and happy.
maxBirdy: (2016-06-25 05:10:34)
Interesting… Amsoil's spec sheet shows 4 pints for the 71C in the Z31. I don't have one to compare to, so my mistake if incorrect. A 3-pack is still sufficient for the transmission alone then.
However, ATF is recommended for the WC T5, not the Non-WC T5 that came in our Z31s. WC T5s came with fiber-lined brass synchros and require ATF to keep the lining intact. Non-WC T5s have standard brass synchros and need a GL-4 type fluid. Run ATF in a Z31's T5 and you'll find that first and second gear synchros can develop a nasty whine.
The transmission is supposed to be filled to the top of the fill hole. I dumped mine, plugged it, and it took about 3 quarts of mt-90, there was a small amount left over.
I have heard that as well, the WC was the only one to take ATF, but I have heard the argument that the non WC can take it as well. I don't know who to believe, and I honestly think nobody knows what they're talking about and its all opinion. I've read about people swearing up and down atf goes in ALL T5's, and others say 75w90 works fine in the non WC too, including the service manual, but there's also some outdated shit in some service manuals.
maxBirdy: (2016-06-25 05:11:39)
I think it was on bobistheoilguy, multiple pages of people bickering over the WC and non WC T5, and whether to use ATF or 75w90.
flatfoot: (2016-06-25 06:24:57)
I can dig out the owner's manual on my 86t and show you where it claims to take either 80w/90 or dex.
Having tried them both I'm a big fan of Redline D4 ATF.
Never thought I'd say it, but the expensive stuff makes a diffence over conventional ATF.
V8srfun: (2016-08-27 10:58:59)
The transmission is supposed to be filled to the top of the fill hole. I dumped mine, plugged it, and it took about 3 quarts of mt-90, there was a small amount left over.
I have heard that as well, the WC was the only one to take ATF, but I have heard the argument that the non WC can take it as well. I don't know who to believe, and I honestly think nobody knows what they're talking about and its all opinion. I've read about people swearing up and down atf goes in ALL T5's, and others say 75w90 works fine in the non WC too, including the service manual, but there's also some outdated shit in some service manuals.
Manual transmissions and all differentials are designed to be fillet to the bottom of the fill hole NOT THE TOP
maxBirdy: (2016-11-16 12:56:32)
Manual transmissions and all differentials are designed to be fillet to the bottom of the fill hole NOT THE TOP
just a note for anyone reading this. this guy is 110% wrong. only listen to him if you like blowing up your differential and transmission.
frostvectron: (2016-11-17 01:09:56)
just a note for anyone reading this. this guy is 110% wrong. only listen to him if you like blowing up your differential and transmission.
No, actually he is right. You fill until fluid starts coming out of the fill hole. How the heck are you supposed to fill the case to the top of the fill hole when it is pouring out of said hole?
kaur: (2016-11-17 06:38:49)
Lift one side of the car higher while filling[archived image: biggrin.png]
At least with the transmission, the FSM also specifically says to fill up to the hole, not higher in any way.
NewJerseyZ: (2016-11-20 18:22:10)
I just changed gear oils in my T5 (FS5R90A) and the rear differential (Quaife). In the transmission I changed from ATF to Liqui Moly GL-3+ and in the rear to Liqui Moly GL-5. Right in front of me is the 1985 OEM Nissan 300ZX FSM and on page GI-13 it specifically states that in the T5 Turbo model one can use either GL-4 or Type DEXRON, which is an ATF. For some reason, non-turbo models cannot use ATF. Liqui Moly GL-3+ is usable for GL-3 and GL-4 applications and is made to work with brass syncros. GL-5 is too slippery for the T5 brass syncros --- and believe me, it is the slipperiest oil I have ever felt.
frostvectron: (2016-11-21 05:28:32)
For some reason, non-turbo models cannot use ATF.
This is likely because the non-turbo models did not use the T-5.
maxBirdy: (2016-11-30 00:21:46)
No, actually he is right. You fill until fluid starts coming out of the fill hole. How the heck are you supposed to fill the case to the top of the fill hole when it is pouring out of said hole?
i meant to say to the top hole. my bad, but seriously how the fuck wasn't it obvious what i meant. i thought the other guy was saying to NOT fill it fully.
daniel_pearce: (2016-12-04 09:39:01)
@OP. Mobil 1 Synthetic Gear Lubricant LS 75w-90 is an API GL-5 product which is intended for extreme pressure protection in differentials and not transmissions. The sulfur/phosphorous content is too high and will corrode the brass synchros in our transmissions.
OK, so I have seen a lot of people asking on z31performance.com and several other forums, "What type of transmission do I use for the to use for the 71C?" and "What type of transmission fluid do I use for the T5." Many folks have recommended synthetic, or ATF, or 50wt, or Redline MT-90 because they say it, "made the car shift smoother." However, I've discovered that some folks really don't know why one type of fluid works better than another. Perhaps they think because it's better because it got good reviews. Some folks heard it through word of mouth. Or maybe it's because one costs more than another, therefore it must be of a higher quality. In order to clear up all of the confusion, I'm posting a short summary of exactly what type of gear oil should be used in the 300ZX non-turbo FS5W71C, 300ZX Turbo FS5R90A (Non-World Class T-5), World Class T-5, and God forbid you have one, the automatic transmissions.
E4N71B Automatic transmission: ATF DEXRON
4N71B Automatic transmission: ATF DEXRON
FS5W71C 5-speed transmission: Nissan recommends API GL-4 (SAE 75w-90)
Non-World Class T5: API GL-4 (SAE 80w-90) or Type DEXRON. The FSM is outdated and things have changed since the Z31 made its debut. I could go into details about DEXRON, but to avoid confusion look for DEXRON III which is still sold, or ATF labeled "Dex/Merc." Buy a trusted brand such as Valvoline.
80w-90 is what I use in my T5 transmission, and it has many additives that provide cushioning for the gears and syncros. It works perfectly fine in the spring and summer months. However, it's thicker in cold weather which can result in slower shifts. That's why some folks recommend using ATF. ATF 10w is lighter so you'll get quicker shifts in cold weather. Synthetic gear oil has the same viscosity as conventional gear oil, but a higher flow rate. Therefore, it will also provide quicker shifts in cold weather. However, I don't drive in the winter months and the car is over 30 years old. In this case, conventional 80w-90 is fine for me. Saves on the wallet. If you drive your Z in cold weather, by all means use ATF or synthetic.
As I stated, DEXRON III or ATF Dex/Merc is recommended for the NWC T-5. but not API GL-5. API GL-5 contains twice as much sulfur/phosphorous as API GL-4 which is corrosive to the brass synchronizers. That will cause your synchronizers to wear out extremely fast. API-GL 5 is needed for extreme pressure protection in the differential where the final torque is applied. The higher sulfur/phosphorous content helps it bond to the brass. API GL-4 is used in the transmission where the extreme pressure protection isn't needed. Only 30% of the torque is applied in the transmission.
World Class T-5: ****ATF DEXRON III****. The World Class T5 came with a sticker on it that said, "ATF Only." They don't use heavy gear oil or Redline MTL.
300zxturboftw: (2016-12-16 18:20:44)
Ummm. I remember reading a pretty old post about GL4 vs GL5 oils. There was a recommendation for Motul Gear 300, which I am currently using… but now I am googling it and a few results pop up saying the Motul Gear 300 is GL4/GL5 (i.e. not good for GL4-only applications)… did something change?
I would change that out immediately. Motul 300 is great stuff (used it in my WRX), but apparently will breakdown the copper synchros. I've been using MT90 for a while now and never had any problems. I'm no scientist though.