- Joined
- Jun 2, 2003
- Messages
- 23,591
And yet the MT-90 is super-smooth in my Audi, which likely has more in common with a Skoda than a Toyota.
Last edited:
Used GL-5 oil in GL-4 transmission, need advice...
- Thread starter Vince58234
- Start date
- Status
And yet the MT-90 is super-smooth in my Audi, which likely has more in common with a Skoda than a Toyota.
Is any gearoil listed for both GL4 and GL5 applications safe for yellow metals (brass synchro)???
Another thing is that if an oil is designed with NON-BORATE additive, does it mean it is safe for brass???
Another thing is that if an oil is designed with NON-BORATE additive, does it mean it is safe for brass???
I'm bumping this up in hpes that there is more info of GL-4 vs GL-5. I am inclined to believe mechtech2 but am just see if other info is available. We had an industry knowledgeable person some years back (believe it was molekule) who indicated there was currently no SAE test for GL-4 and GL-5 was the standard.
Whoever told you, is correct there is no test specification or tests to prove GL-4 performance. GL-4 oils are mostly simply an arbitrary downtreat of the GL-5 additive (usually about 50%). This is because, as I think someone said earlier, GL-5 additive treat level is usually too slippery to allow the synchronizers to operate correctly.
The problem with swapping or choosing fluids to use in manual transmissions is that most manual transmissions not only obviously use a synchronizer material, but they usually use more than one. When the manufacturers select a fluid they run comprehensive synchro tests on all of those material combinations to ensure that the fluid chosen is going to work long-term in concert with all of those materials, without causing excessive synchro wear, clashing, harsh or notchy shift or other such problems. So you'll see that choosing to use a different product (other than the manufacturer recommended one) can be risky. Hope that helps.
The problem with swapping or choosing fluids to use in manual transmissions is that most manual transmissions not only obviously use a synchronizer material, but they usually use more than one. When the manufacturers select a fluid they run comprehensive synchro tests on all of those material combinations to ensure that the fluid chosen is going to work long-term in concert with all of those materials, without causing excessive synchro wear, clashing, harsh or notchy shift or other such problems. So you'll see that choosing to use a different product (other than the manufacturer recommended one) can be risky. Hope that helps.
Thanks a lot. I really appreciate the information.
I'm at 100K miles now with my car; so 30K with the current fill of Redline MT-90 and the shifting is just awful. It takes awhile to get into gear and it feels very notchy in the process. Can I hide this problem somehow with a thicker oil? My tranny requires GL-4 75W-90 per VW.
Thanks
Thanks
Originally Posted By: kilou
Is any gearoil listed for both GL4 and GL5 applications safe for yellow metals (brass synchro)???
Alright, let's get up-to-speed so the GL thing can be common knowledge. I'll add what I can.
GL-4 & GL-5 do not supercede, that is 5 is not better or newer than 4, they simply describe gear oils with different coefficients of friction. (some brands claim both!?) GL-5 usually incorporates the MT-1 spec to assure yellow metal compatibility. MT-1 means ok with yellow metals...."MT" indicating manual trans, although it's more specificly a gear oil.
Witness Mobil's webpage, it'll say something like- will not corrode yellow metals. That whole mythology needs to die. The differing friction characteristics will affect the shifting, and that might be the problem described.
Is any gearoil listed for both GL4 and GL5 applications safe for yellow metals (brass synchro)???
Alright, let's get up-to-speed so the GL thing can be common knowledge. I'll add what I can.
GL-4 & GL-5 do not supercede, that is 5 is not better or newer than 4, they simply describe gear oils with different coefficients of friction. (some brands claim both!?) GL-5 usually incorporates the MT-1 spec to assure yellow metal compatibility. MT-1 means ok with yellow metals...."MT" indicating manual trans, although it's more specificly a gear oil.
Witness Mobil's webpage, it'll say something like- will not corrode yellow metals. That whole mythology needs to die. The differing friction characteristics will affect the shifting, and that might be the problem described.
Thicker is probably going to make it worse IMO. Pick up some Lubromoly or Motul 75w-90 as stated earlier since your in Germany. Another choice would be VW G50 GL4 which is available at the dealer, but it's expensive.
I ended up dumping my MT-90 after 25k in my VW after it became notchy as well (especially reverse). I still like MTL-R though, but SF is no longer is business.
I ended up dumping my MT-90 after 25k in my VW after it became notchy as well (especially reverse). I still like MTL-R though, but SF is no longer is business.
- Joined
- Dec 30, 2006
- Messages
- 29,558
I emailed Mobil some time back asking about their gear oils and they said not to use them in any manual transmission. Redline MT90 made mine very notchy as well just as par stated in his response. Sta Lube GL4 brought new life to my very finicky tranny. Smooth as silk. Seems to be smoothing out the more I drive it. So far the notchiness is going away. All gears feel very "cushioned" when shifting. Hope this trend continues.
I recommend GL-5 Mobil 1 for service in diffs, but it's too slick for trans, although some guys use and like it. Audi quattros have 3 diffs, and guys buy the same exotic oil for all 3, plus the trans. I don't think it's wrth using anything other than Mobil 1 in the diffs, but in the gear box...shure, try different ones, any brand you fancy, and change it often.
- Status
Similar threads
