Can I Use 75W-90 In Place Of 75W-85?

[zeng]

That's right,a specific model of ZF manual transmission would specify viscosity grade ranging from 75W80 to ... 80W90 ... SAE 90 etc.... depending on ambient temperatures and vehicle applications.

Therefore,an oil of 'heavier' viscosity grade than that specified by OEM cannot be causing harm ...... instead ,every other things being equal, it would enhance components longevity from higher operating viscosity.

 

[MolaKule]

Quote:
Redline makes MT85 at $17 a quart. Amsoil makes an MTF 75W-90 for $11 a quart. I talked with Amsoil and their tech said NO they do not make a fluid for my car because the viscosity is not the OEM spec so they will not suggest that I use it.


I am surprised the Amsoil tech didn't suggest mixing the MTG with the MTF, but maybe there may have been some liability issues with suggesting that.

I know many complain about the high cost of MTF's but if you look at the total capacity of the tranny vs. cost vs. how many times you change it, using a good, dedicated synthetic MTF is not really that expensive.

And again, a good fluid with periodic changes is much less expensive than tranny rebuilds or tranny replacements.

 

[MolaKule]

Quote:
The Nissan fluid does not use sulfur/phos additives, but a special magnesium EP compound. It is also synthetic.


The Nissan fluid does use a phos anti-wear component, but the Magnesium compound is not an EP compound.

Special Magnesium or calcium compounds in dedicated MTF's are part of the friction modification chemistry.

 

[kyoo]

the Mitsubishi evo's 6spd is a terrible gearbox and as I understand they had a 75w85 designed around it. I didn't know this and had been running 75w90 - the 75w85 feels much, much better.