GL4 vs GL5

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Mr.Fork

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Hey guys,

I recently had replaced my gearbox oil with 100% synth GL4 75W90 for my 1999 Maxima SE.

I had the main seal replaced, and the mechanic topped it up with GL5.

On the Maxima.org forums, they strictly recommend staying with GL4 oil, as GL5 additives are bad for the syncros.

How accurate is this? Should I be running to replace the gear oil again? I had a real hard time finding Mobile GL4 oil last time (took almost a month).

Forkster
 
Depends on the lube used. I had a 97 and it shifted good on Amsoil's GL5 stuff back then, others on that forum noticed more of a difference with Mobil 1 and degraded shift feel. There are some on there that swear GL5 lubes killed their tranny. Nissan's 5 speeds from that era just failed anyway from the diff bearings, not because of the lube (IMO). If it's notchy to you, I'd change it.

Both Amsoil and Redline now have excellent GL4 MTF's that won't harm the synchros.
 
I've heard the same thing mdv. Guess the question is on whether or not GL5 is bad for the syncros? Or better yet, does using GL5 oil just make the bad gearboxes more apparent?

I have GL5 in mine now mixed with GL4. It's ok, but it worries me that the GL5 additives might damage the gearbox.
 
What's the capacity? How much top-up did he add?

I'd probably change it for peace of mind. I've been using Redline MT-90 in my manual trannies.
 
The issues with GL5 is that it contains additives that are harmful to brass synchros. That's why for example GL5 is not recommended in most VAG trannies. Does the Maxima use brass synchros?
 
Synthetic GL 5 like M-I are non corrosive to brass, so is boron based Delo GL 5 from Caltex, also Elf Transaxle GL5 comes with soft metal protector additives.
 
Hi Pete - the Maxima's indeed to use brass synchros. I'll think that I'll swap it out when I get a chance. He had to use 1l of the fluid (gearbox takes 4).
 
The manual transmission for my 2006 Toyota Corolla calls for GL-4 or GL-5 75W-90. My local dealer uses GL-4 and to be on the safe side I have changed out the initial fill at 4k miles and replaced with Redline MT90 full synthetic 75W-90 GL-4 and will probably do 4 year/30k mile changes.
Roger
 
I will save you a little time
smile.gif


http://www.soslube.com/
 
So is the answer then any GL5 is ok as long as it's MT-1 classified?

moribundman - I still didn't determine anything from the other forum. They were just as confused as the rest of us.
 
We have now begun to use the Amsoil MTF and the 75W-90 MTG, both GL4 lubes and have had excellent results so far with both. In the past the Redline has done well also, MTL and the MT-90. I have been wanting to use the products from Specialty Formulations, a sponsor of BITOG, as many people have had excellent results from his gear lubes and other products. The biggest issue for GL-5 is is supposedly has 10X the EP wear additives in it, and older formulations in times past were known to attack soft metals such as the brass synchros in a manual gearbox. I don't believe that is as true in most current formulations of GL5. I would not worry too much about the one liter of GL5, especially if it is MT-1 rated as well, unless of course shift feel changes for the worse.
 
roger & bmwtechguy - thanks for the feedback and advice. I'll get it swapped out tomorrow. I've noticed it's been feeling a little notchy when shifting lately. I'll use Redline MT-90.

I also noticed that Canadian Tire had a synth blend GL-4/GL-5 MT-1 75W-90 gear oil but I'm nervous about using it since it's also GL-5 compatible.
 
Quote:

... The biggest issue for GL-5 is is supposedly has 10X the EP wear additives in it, and older formulations in times past were known to attack soft metals such as the brass synchros in a manual gearbox. I don't believe that is as true in most current formulations of GL5. I would not worry too much about the one liter of GL5, especially if it is MT-1 rated as well, unless of course shift feel changes for the worse.

Click to expand...

I think most modern GL5's have about twice the antiwear additive package as GL4 and aren't corrosive to brass. The MT-1 rating is for non syncro heavy truck transmissions. I doubt if 25% GL5 would hurt anything. The GL5 might be too slippery and make the shifting seem balky.
 
Yeah, don't worry about it.
But, depending on the additive package used, and its buffering capability, consider an early fluid change out. Never run any gear oil over 30k miles with a UOA to monitor wear and TBN/TAN.
 
Quote:

Yeah, don't worry about it.
But, depending on the additive package used, and its buffering capability, consider an early fluid change out. Never run any gear oil over 30k miles with a UOA to monitor wear and TBN/TAN.

Click to expand...
 
Quote:

So is the answer then any GL5 is ok as long as it's MT-1 classified?

moribundman - I still didn't determine anything from the other forum. They were just as confused as the rest of us.

Click to expand...


The corrosive effect of modern GL5 fluid on yellow metal parts appears to be limited to temperatures higher than those encountered during street driving. I believe there used to be a link to another Mobil statement regarding this issue in this thread, but I can't find it now.

I also remember the API introduced the MT-1 spec to address the possibility of yellow metal corrosion. Lubes that meet MT-1 will not attack yellow metal up to temperatures of 250 degree F. Touch your car's transmission after a spirited drive and see if it's anywhere near 250 F.
 
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