GL4 or GL5 for manual transmission?

[Jetronic]

It appears it's made for a purpose. High load or high HP/TQ applications. Like a 500 to 800+ HP Subaru WRX or EVO with the same high HP/TQ. Porsche/Ferrari/Alfa Romero certs are on the NS series too I would assume for high load manual gearbox using the same cavity as the diff is.

I know when towing a 1,200 lbs boat in my Kona AWD (world car) where the max tow in Europe/Aus is 2,800 lbs. I get a "load" noise on the front diff if towing in FWD only. I hit AWD and it goes into a 95/5 split that a Rav4 also does and the front diff load goes away, as 2 diffs are sharing a load now. I too would benefit from the NS series with my Kona in the towing scenario. I have upped my fluid from the 70w-75 Gl-4 factory spec to a non CAFE 75W-85 GL-4 as suggested by a Redline R&D chemist that I got through to when Dave was on vacation. I never talked to him about the NS series.That is an option when I start putting 325+ ft TQ through it next year.

The lower tow limit in the US will be due to the higher towball download compared to Europe, 10% of tow weight vs 5-6% in Europe.

 

[weasley]

Transaxles for front wheel drive vehicles are connected to the hubs via half-shafts and Constant Velocity Joints.

Fair enough - in my mind a transaxle is the combined transmission/axle used in some RWD applications; I admit I'm not familiar with the specific car in question.

 

[Elkins45]

There are better ones out there.


The next higher viscosity MTL would be the 7.0 to 7.6 cSt@100C versions (SAE 70W75, 75W80) (About the same viscosity as the original DexronIII/Merc)

Royal Purple's Synchromax
Ravenol MTF-2
Honda MTF
VW part number G052512A2
BMW (Pentosin MTF 2) MTF-LT-1, 2 ,3
Tutelo (Petronus, Italy, Product Code 1402)
Pentosin Pro Gear 70W75 (Australia)
Pentosin FFL-4
Redline Power Steering Fluid
RAVENOL STF

I'm very appreciative of your advice and very respectful of your obvious knowledge, but please forgive me if I push back just a bit. You're telling me that I would be better off putting a product labeled as a power steering fluid (Redline) than a product labelled as a manual transmission fluid in my manual transmission? That's difficult for me to wrap my head around.

It's also hard to wrap my head around the fact that Mazda specs a transmission fluid that's basically unobtainable without hunting down some boutique maker's product or some fluid that's only available from a handful of sellers online? I'm curious what the Mazda dealer I bought it from has on the shelf. Next time I'm in town I'm going to stop by the parts department and see if they sell a replacement fluid or if the guy just grabs a bottle of GL-5 gear oil. Or if they do have a proper fluid but it's $40/quart

Edit: I think the Honda fluid should be fairly easy to find without ordering it.

 

[MolaKule]

I'm very appreciative of your advice and very respectful of your obvious knowledge, but please forgive me if I push back just a bit. You're telling me that I would be better off putting a product labeled as a power steering fluid (Redline) than a product labelled as a manual transmission fluid in my manual transmission? That's difficult for me to wrap my head around....

I stand behind the suggestion because I have analyzed it in detail. It contains a hefty anti-wear chemistry, it has friction modifiers for synchro assemblies, and has a 7.0 cSt@100C viscosity, with good shear stability. The DI package is essentially the same as that for their manual transmission fluids, only in a lower viscosity base oil mix.

So it IS suitable for any manual transmission requiring a 70W75 or 7.0 cSt GL-4 MTF.

 

[Elkins45]

I stand behind the suggestion because I have analyzed it in detail. It contains a hefty anti-wear chemistry, it has friction modifiers for synchro assemblies, and has a 7.0 cSt@100C viscosity, with good shear stability. The DI package is essentially the same as that for their manual transmission fluids, only in a lower viscosity base oil mix.

So it IS suitable for any manual transmission requiring a 70W75 or 7.0 cSt GL-4 MTF.

My transmission requires 75w-80. Does that matter?

 

[MolaKule]

My transmission requires 75w-80. Does that matter?

Have your current OEM MTF fluid analyzed to determine it's actual 100C viscosity before selecting any MTF fluid.

Viscosity Charts - Bob is the Oil Guy

Viscosities can be related horizontally only Viscosities based on 96 VI single grade oils. ISO are specified at 40°C AGMA are specified at 40°C SAE 75w, 80w, 85, 5w, & 10w specified at low temperature. Equivalent viscosities for 100° & 210°F are shown SAE 90 to 250 and 20 to 50 specified at...

bobistheoilguy.com

The point is, the viscosity charts for SAE gear oils (XXWYY) describe a "range" of viscosities, and this cannot be stressed enough.

 

[Sequoiasoon]

MolaKule has always provided great information. One of the threads way back he had many transmission fluids and their respective viscosities etc.

I had an older '93 Corolla with over 100k that was a light grind at higher rpm and under load. Many different fluid changes, factory, name brands etc. Shop and somewhere else said needed rebuild. Friend recommended BG Synchro Shift II as they were using it at BMW he worked as mechanic to help clear some of the same issues. I bought it and replaced fluid, hoped for fix, figured $45 loss at worst. About 30 miles later all grind was gone and stayed gone for the next 120k until it was totaled. I replaced every 2 years anyway with same BG just to keep it fresh.

The BG fell right in line with some of the synchromesh iirc.

As explained to me then, the slightly lower viscosity and whatever else put less drag on the synchro's letting them work as they should. Whatever it was $45 was much more economical than a tranny rebuild.

 

[Elkins45]

I went by the Mazda dealer where I bought my car and asked about manual transmission fluid. It’s 75w-80 gear oil and it’s $29/quart.

I left without buying any.