Always GL5 vs GL4 but also grade question

[kilou]

Hi

I’m so glad to have found such a forum dedicated to oils  I’ve been seeking information on gearbox oils since a long time without much success and I’m sure with all the bunch of experts here that I will soon learn a lot about this topic ! However I live in Switzerland and my car is not available in the US market (both engine and gearbox) so I don’t know if you have information about it……..ok let’s go but it will be looooong.

Well my interest in the topic of gearbox oils has born since my gearbox developed a grinding noise when upshifting from first to second gear when cold. I’ve been seeking informations on how to cure or lessen this by using another type of oil than the factory fill one.

In this thread I will ask information about the API rating and the grade of oils to be used in my transmission. First some information about my car:

Volvo S40 2.0 140hp
Manual 5 speed transmission (badged M5P by Volvo)

This transmission is built by Renault (French car manufacturer) and is badged JC5-222 by Renault. First I started to ask information by Volvo but they don’t know anything about the oil type used in my gearbox. So I went to Renault and they said my gearbox calls for a 75W80 API-GL5 oils which is called TransElf TRJ (from Elf).

Now my questions:

- I know that GL5 oils can be corrosive to brass synchronizers BUT I also learned on this forum that most GL5 oils use the “inactive” sulfur-phosphorous additive pack that makes them suitable for use in gearboxes containing yellow metal. Does anybody knows if the TransElf TRJ 75W80 GL5 oils contain “inactive” EP additives (I can’t contact Elf despite numerous emails)?

- Aside of the problem of brass corrosion of GL5 oils, after discussion with Redline Oils staff, it seems that GL5 oils are commonly too slippery for synchronizer due to the high amount of EP additives. They told me this is the case for all GL5 oils even those that state they are suitable for synchronized gearboxes and that GL4 have better frictional properties compared to GL5. So is it possible to use a GL4 oil such as Redline MTL in my transmission although Renault recommends a GL5 oil for it? In other terms, is the GL5 recommendation of Renault really important or is it only because GL5 are more common than GL4 oils?

- Now about the grade, Redline told me that a thin gear oil would help in cold shifting. In this case a 75W80 would be fine. However the hot grade 80 seems a bit low for high temperatures (I often drive on highway with outside temperature of 30-35°C) and I believe a 75W90 oil may be “safer” for operating temperature. The problem is that after comparing real viscosities (in cSt) when cold (40°C) of 75W80 and 75W90 oils, I found that although they share the same cold index (75W), 75W90 oils have almost twice more viscous than 75W80 oils when cold (40°C)!!!!!!! I told this to edline staff and they explained me this is because the 75W grade is wide and 75W80 will be in the lower end while 75W90 will be in the higher end. So first is it safe to use a 75W90 where a 75W80 is recommended and will the use of a 75W90 oil introduce more shifting problems when cold compared to a 75W80 oil? In any case is it recommended to use a 75W90 rather than a 75W80 to cure a shifting problem when cold?

- Which oil would you recommend for my transmission providing all the above information?

Best regards

 

[MolaKule]

You may have to experiment a bit like most of us here.

I would first try the Redline MT90 (GL4). It has plenty of AW/EP protection for your spur gears in the (I assume) Manual Transmission. If that doesn't suit you, then ratchet up to the 75W90 GL5.

[ June 03, 2004, 04:02 PM: Message edited by: MolaKule ]

 

[JohnBrowning]

I agree with Molakule try MT-90 first!

 

[Audi Junkie]

My inner skeptic says GL-4 is a marketing niche. I just ordered Motul gear lube, meets both GL-4 & GL-5.

http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=16;t=000442#000000

 

[kilou]

But will using a 75W90 instead of a 75W80 emphasize cold shifting problems due to the higher viscosity? If my transmission calls for a 75W80, Redline MTL would be better than MT-90 no?

Viscosities in cSt at 40°C (cold)

TransElf TRJ 75W80 (my actual oil): 47
Redline MTL 75W80: 56
Redline MT-90 75W90 : 90

MT-90 has TWICE the viscosity when cold compared to my actual oil! So I suppose this is not good for cold shifting (even MTL has a higher viscosity than my oil though).

Concerning GL4 or GL5, I'm a bit afraid to make some bet because I suppose I won't feel soon enough if my gearbox has sufficient EP additives or not! It's a bit risky no? Usually the question is the opposite: manual gearboxes call for a GL4 lub and you want to experiment a GL5. With the "inactive" EP package, this isn't a problem anymore and you may experiment but doing the opposite is tricky because not enough EP additive would inevitably cause quick premature wear of the gearbox!

 

[kilou]

But will using a 75W90 instead of a 75W80 emphasize cold shifting problems due to the higher viscosity? If my transmission calls for a 75W80, Redline MTL would be better than MT-90 no?

Viscosities in cSt at 40°C (cold)

TransElf TRJ 75W80 (my actual oil): 47
Redline MTL 75W80: 56
Redline MT-90 75W90 : 90

MT-90 has TWICE the viscosity when cold compared to my actual oil! So I suppose this is not good for cold shifting (even MTL has a higher viscosity than my oil though).

Concerning GL4 or GL5, I'm a bit afraid to make some bet because I suppose I won't feel soon enough if my gearbox has sufficient EP additives or not! It's a bit risky no? Usually the question is the opposite: manual gearboxes call for a GL4 lub and you want to experiment a GL5. With the "inactive" EP package, this isn't a problem anymore and you may experiment but doing the opposite is tricky because not enough EP additive would inevitably cause quick premature wear of the gearbox!

 

[TooSlick]

Some of the older Volvo manual transmissions actually called for automatic transmission fluid, which is an SAE 5w-20 or 0w-20 fluid. The Redline MTL should be excellent for this application if it calls for a 75w-80 - it's a 70w-80, which is roughly equivalent to an SAE 5w30 in terms of low/high temp viscosity and very shear stable....

You'll do more damage grinding gears in the cold than by using a slightly thinner fluid that flows well and reduces fluid temps in hot weather ....

Tooslick
www.lubedealer.com/dixie_synthetics

 

[TallPaul]

Just be aware that a thicker oil in a manual transmission that specs ATF could be a problem. One guy at the Ford Truck site reported a Mazda 5-speed (M5OD) in an F150 that burned up the two front gears because the guy ran gear lube which changed the way the splash oiling went and allowed these gears to run dry. That's why I am going with Redline D4 ATF as it is thinner than the MTL. Not to say MTL won't work, but the D4 is the same as the Mobil 1 Mercon I had been running and my M5OD specs Mercon.

 

[Bror Jace]

kilou, MolaKule gives some of the best advice when it comes to gear oils ... especially in synchromesh transmissions.

However, one approach I'd consider is to go with the MTL (last labeled 70W80) and change it fairly often ... no more than 30,000 miles (50,000 KM). The additive package (even if it's skimpier than a GL5) won't be depleted in such a short amount of time.

In Switzerland, do you have access to a lab which can do a used oil analysis? It might be interesting to see how MTL is holding up.

However, as was said before, be prepared to experiment a little ...

... and take it easy shifting that transmission. If you are getting grinding, the synchros have already experienced some wear/damage. No oil is going to fix that.

--- Bror Jace

 

[kilou]

Thanks for all your replies. The problem is that Redline oils are hardly available in Europe. The only dealer is located in United Kingdom and shipping costs are rather prohibitive!

The griding of gears only occurs when cold for 2 or 3 shifts from 1st to 2nd gear. All other gears never grind and when the temperature grows up, the gearbox is very smooth. So I believe this may be "healed" by changing the oil although as you said the synchros must start to be worn out (the car has 220'000km on the clock).

Before experimenting, I'd like to know the properties of Volvo's recommended oil. Now I use another one (TransElf TRJ) which works rather well but it would be nice to know what Volvo exactly uses (GL5 or GL4, viscosities etc). All I know is that Volvo oil is a 75W80 oil with EP package (so I bet it's a GL5). However Volvo is totally unable to give me more informations about their gear oil.

Do you know who is manufacturing gear oils for Volvo?

 

[MolaKule]

As I stated earlier, you might have to experiment with various fluids to find one that shifts well in cold weather.

Unless you have an awfully tight transmission, I would not go below a 10 cSt @ 100 C fluid. I do know that Nissan transmissions don't shift well with fluids above about 13.5 cSt @ 100 C.

If you look at the additive packages, MT90 and MTL have the better AW/EP specs than any of the ATF fluids. This is why I would start with MT90 in the summer and then go with MTL in the winter OR use a 50/50 mix of MTL/MT90.

If you MUST go with an ATF, use the Synthetic High Temp ATF @ 10 cSt.