GL-4 or GL-5

[BrandonVA]

I have an '06 corolla. Everywhere i'm reading people are suggesting to use MT90 which is a gl-4 oil. amsoil recommends gl-5 oils like severe gear. Toyota specs GL-5.

What should I use? Severe gear is a GL-5 that is also speced for GL-4 applications. That seems to be the most ideal fluid besides Toyota OEM fluid.

What are the differences between the two and why should I use GL-5 over GL-4?

 

[jrmason]

The primary difference between the two specs is the amount of extreme pressure additive package. GL4 has roughly half the EP additive as GL5. GL5 is designed more for hypoid gear interfaces while GL4 is generally designed for manual transmissions. Without being familiar with your transmission I won't comment on which is better to use, but generally speaking the OEM recommendation is a safe bet.

 

[QuietPortage]

If Toyota calls for it, GL-5 is the way to go.

 

[oilboy123]

Amsoil used to say to use one of their gear lubes like you mentioned. They now want you to use one of the below fluids assuming it's for the trans.

http://www.amsoil.com/shop/by-product/transmission-fluid/manual/

 

[SkyActivG]

The only motor oils that I know were GF-5 from they get go were Eneos and Idemitsu Z-Pro. I think it's safe to run a GF-5 in your corolla. I think it'll have far better anti wear additives

 

[Revving2Redline]

no, run gl4 in front wheel drive std transmissions. the synchros cant handle gl5. call dave at redline and i bet he says to run mtl or mt90. gl4 offers the right amount of slip and isnt hard to shift.

 

[simple_gifts]

What is the source of GL5 recommendation; my toyota takes GL4 or GL5;

Quote:

MANUAL TRANSAXLE
Oil capacity, L (qt., Imp. qt.):
1.9 (2.0, 1.7)
Oil type:
Gear oil API GL–4 or GL–5
Recommended oil viscosity:
SAE 75W–90


edit:I checked the OM for your car on the Toyota website; the spec is GL4 or GL5

Redline MT90 or Amsoil MTG is a good choice.

 

[FowVay]

I have two friends with these vehicles and they both use MT-90 (GL4). I'd say that since the manual allows for a GL5 fluid then maybe the transmission isn't susceptible to the corrosion of the soft metals.

I think that the desire to use MT-90 is driven by shift quality. 75W-90 may be a bit viscous at low temperatures.

 

[JerryBob]

I asked the same question about the MT in my Tacoma. Here is the thread:

https://bobistheoilguy.com/forums/ubbthreads.php/topics/3415164/Re:_Toyota_MT_-_"Gear

 

[Al]

Many many years here on BITOG there was a lengthy discussion about GL-4 vs GL-5. At that time a very respected poster indicated that there was no longer equipment to certify GL-4 specs. He indicated (as I recall) that there was no problen any longer with corrosion of higher EP GL-5 products (used in GL-4 applications) due to their improved chemistry. I thought that poster was Molakule..but I could be wrong.

The whole discussion ultimately went nowhere. I would certainly like to know the answer to this question, "can GL-5 oil be used where GL-4 is specified?"

 

[gathermewool]

There are gear lubes that are dual-rated, that don't use yellow metal-corroding EP additives (sulfur/phosphorous, IIRC,) but I haven't found any that are cheap.

My previous STI called for GL-5 all around, but the MT shared it's bath with the LSD in the front, so downgrading to a MTF or Gl-4 wasn't an option. Motul Gear 300 (dual-rated) worked well (I don't recall which EP additive pack, but it didn't smell sulfuric to me,) but shift quality degraded after a couple of years.

I then tried Redline's GL-5 75W90NS (sulfur-based EP, based on smell and an internet search, but an appropriate level of friction modifiers for synchro engagement) which worked well and improved shift quality. I only had it in the sump for a short period of time before I traded the STI.

//

I don't know much about your Transmission, so I can't say whether GL-5 is in the spec because Gl-4 is hard to find or if your diff could benefit from the extra EP additives. I don't think going crazy with something like Severe Gear or even Motul Gear 300 is necessary, but being the true BITOG'er that I am I'd probably find a quality dual-rated Lube and probably never think about changing it again for the life of the car.

 

[brandini]

If it says a GL4 is fine in a transmission, likely it'll be better than a GL5 in shift feel and synchro friendliness. GL5 will coat the gears and synchros so they'll not grab onto one another and make shifting difficult.

Hey look, another Brandon in VA!

 

[4wheeldog]

Originally Posted By: brandini
If it says a GL4 is fine in a transmission, likely it'll be better than a GL5 in shift feel and synchro friendliness. GL5 will coat the gears and synchros so they'll not grab onto one another and make shifting difficult.

Hey look, another Brandon in VA!


This is correct. For years, Toyota has specified GL4 or GL5 in manual transmissions. The GL5 does not let the synchros do their job. Try Redline MTL90 in your Toyota manual transmission, you will never go back.

 

[Rand]

There are no hypoid gears in that transmission so use GL-4 for better shift feel.

There are quite a few good ones. MT90 is definitely very good.

 

[Drew99GT]

Are you certain your Corolla specs GL-5? In the owners manual and factory service manuals, Toyota specs GL-4 OR GL-5 from what I've seen.

Be careful with GL-5s since many of them today have limited slip additives which will not be good on a manual transaxle.

I've used just about every fluid available in my Corolla and it likes conventional gear oils the best for whatever reason. I have 3 bottles of Motorcraft conventional GL-4 75w-90 waiting to go in after this run of Valvoline GL-5 (old formula without limited slip additives) runs it course. Every synthetic GL-4 I ever tried made shifting very notchy.

 

[Greasymechtech]

Toyota Mazda and several other automakers spec GL4 or GL5 sae90 80w90 75w90 or 75w85. Key word is 'or'. Yes, you can use gl5 gear oil.

As already mentioned, avoid gear oils with LS additives.

Yellow metal GL5 fear is over hyped. The additive package will protect those metals for a finite time. Moisture/water, LS additives, excessive time or mileage on gear oil with exhausted additive package, low fluid level, and excessive heat, are some real problems often blaming the "GL5" label.

I recommend GL4. Redline, Amsoil, Ford, Nissan, GM, Hyundai... have excellent products.

 

[MolaKule]

Originally Posted By: Al
Many many years here on BITOG there was a lengthy discussion about GL-4 vs GL-5. At that time a very respected poster indicated that there was no longer equipment to certify GL-4 specs. He indicated (as I recall) that there was no problen any longer with corrosion of higher EP GL-5 products (used in GL-4 applications) due to their improved chemistry. I thought that poster was Molakule..but I could be wrong.

The whole discussion ultimately went nowhere. I would certainly like to know the answer to this question, "can GL-5 oil be used where GL-4 is specified?"


There are other threads that explained this very well.

First, some review:

Manual Transmission Lubricants

Second, let's dispel some myths.

The GL-X rating defines the protection level for gearing, whether it be transmissions, TC's, or differentials.

A GL-5 rating is for highly-loaded gears (high tooth contact forces), such as for hypoid differentials, and contains high levels of primary and secondary Extreme Pressure (EP) additives such as Sulfur-Phosphorus chemistry. The viscosity of said GL-5 gear lubes is usually higher than for manual transmission lubes. For example, a 75W90 GL-5 gear lube has a viscosity of 18.5 cSt@100C, whereas a GL-4 protection rated 75W90 Manual Transmission lubricant would have a viscosity of 14.0 cSt@100C. This difference in viscosity can have a major impact for Manual Transmission shifting performance in terms of cold weather shifter fork movement.

A GL-4 rating is for lower loaded gearing such as for manual transmissions (MT) and Transfer cases (TCs) in light trucks and cars. It contains mostly an Anti-Wear additive (AW) in the form of ZDDP or an equivalent anti-wear package. It does not contain Extreme Pressure (EP) additives. Furthermore, the GL-4 chemistry for MT's contain specialized friction modifiers for the synchronizer assemblies.

The GL-4 Performance Improvement package (additive package) has been tested by the additive suppliers to perform to GL-4 protection levels using modern testing machines.

For manual transmissions that share the same sump with hypoid differentials, such as the Subaru drivelines, a special GL-5 lubricant is used which has the synchromesh friction modifier. But this is an exception.

If your vehicle specs a 75W90 for your manual transmission or transaxle, these MT lubes should work just fine:

Amsoil MTG or Redline MT-90.

Quote:
I would certainly like to know the answer to this question, "can GL-5 oil be used where GL-4 is specified?"


So the answer is, NO, not for Manual Transmissions.

 

[BrandonVA]

yea, i misread the manual. It does indeed say gl-4 or gl-5. Anyway, I just want the best possible protection for my transmission.

 

[Rand]

Originally Posted By: BrandonVA
yea, i misread the manual. It does indeed say gl-4 or gl-5. Anyway, I just want the best possible protection for my transmission.


Which part of your transmission? Rhe gears will be protected perfectly fine with the gl-4 additive package. EP additives are not needed for "your type of transmission gears" . An example of a gear needing EP additives would be hypoid gearing(which you dont have in your transmission)

GL-5 in your transmission is not needed for protection and will most likely shorten synchro life and/or provide bad shift feel.

So you cant just think "which provides the best protection oh gl-5 has more additives its better"

Its which works best in my manual transmission and that is GL-4.. Plenty of protection and good shift feel, synchro engagement.

 

[circuitsmith]

Originally Posted By: FowVay
I think that the desire to use MT-90 is driven by shift quality. 75W-90 may be a bit viscous at low temperatures.


I used to use MT-90 in my 2006 Matrix, but MT-85 shifts better in the cold.