MoS2 additives get abrasive

[kilou]

http://www.l-fp.com/articles/0304/better_than_syth.html

Reading this article, I found that Molybdenum disulfide (MoS2) additives submitted to heat in excess of 343°C form Molybdenum trioxide which is abrasive!!!!!! Is this true?

Moreover, it is sais that MoS2 cannot handle acids so it means that it is definitely not good as a oil additive?

I'm looking for a gearoil additive to help with cold ****ing. As some of you yet know, I cannot change for a better oil since my gearbox calls for a very specific formulation that is not common: 75W80 GL5 with a viscosity at 40°C lower or equal to 47cSt (my actual oil): this is almost impossible to find (the 47cSt is not a requirment but higher viscosities at 40°C make the gearbox much more hard to shift when cold). I'd like to know if using MoS2 gearoil additive may help but reading this article, I'm a bit skeptical. Would a ceramic based gearoil additive (TecFlow etc) be better than MoS2 for this application?

 

[MolaKule]

As usual, the author of this article presents just enough general information to be dangerous. He does not appear to make a distinction between soluble moly and moly disulfide powders, which is inexcusable for a so-called tribologist.

Any 75W90 synthetic should suffice in your application.

 

[Motorbike]

Kilou ,

It sounds like you need the Tranself TRZ 75w-80

It replaces Volvo 97308

The maker of the factory fill for your car is located in the country you live in BTW

 

[ebaker]

If your trans has syncromesh the moly could cause problems. Also 343C. is over 600F.

 

[BIGJ552000]

quote:

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Originally posted by kilou:

I'm looking for a gearoil additive to help with cold ****ing.

---

I'm NOT too sure if we can help with that!!!J/k

 

[tdi-rick]

'bike, IIRC, that's what he is already using.

cheers,

Rick.

 

[tdi-rick]

quote:

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Originally posted by kilou:

I'm looking for a gearoil additive to help with cold ****ing.

---

Castor oil

Rick.

 

[Motorbike]

quote:

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Originally posted by tdi-rick:
'bike, IIRC, that's what he is already using.

cheers,

Rick.

---

Thanks , I searched and found this
http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=16;t=001127

and this

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=16;t=001108

I'm not certain gear oil is the problem from the description .

Does this trans use pucks on the syncro rings ?

 

[kilou]

quote:

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Originally posted by Motorbike:
Kilou ,

It sounds like you need the Tranself TRZ 75w-80

---

The TRZ is a GL4 and I must use a GL5. Moreover I cannot use a 75W90 instead of a 75W80. A friend has tried a very good 75W90 100% synthetic gearoil (Motul Gear 300) in the same gearbox as mine (calling for a 75W80) and he had very difficult gearchange when cold. This was due to a too high viscosity when cold (indeed even if both are 75W, a 75W90 oil remains thicker when cold compared to a 75W80). He went back to the original semi-synthetic oil and gearchange where much better (but not as good as I'd like them to be...).

The main problem for me is to find a 75W80 GL5 gearoil with a 40°C viscosity lower than 47cSt (the one of my actual oil). Even Redline MTL (in any case a GL4 but...) have a higher viscosity and I believe this is the key point for my application. From the lack of existence of any other thin gearoil but mine, I thought I may benefit from an additive but there is so much troubles with these that I can't decide.

Do you think a MoS2 would improve cold shifting (by coating the the metal)? But you said it may cause problems with synchros?

Graphite additives?

So what about a ceramic based additive?


...or maybe just live with the stiffness of gearchange when cold.......

 

[Pablo]

I don't think you need something more slippery, just a bit lower vis. If you can get stuff from the uk you can get Amsoil Series 2000 75W-90.

 

[kilou]

quote:

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Originally posted by Pablo:
I don't think you need something more slippery, just a bit lower vis. If you can get stuff from the uk you can get Amsoil Series 2000 75W-90.

---

My car calls for a 75W80, not a 75W90. Despite the same cold index (75W) any 75W90 will still be more viscous when cold compared to a 75W80. Remember my actual oil has a viscosity at 40°C of 47cSt!!!!!!! To my knowledge, there is NO other oil with a GL5 rating (and even with a GL4) that has a lower viscosity than this. I found only one oil in the Netherlands that is 45cSt at 40°C but this is not significantly lower to make any difference. Even Redline told me that I would have better results when cold by using my actual oil rather than pouring in their MTL!

My gearbox is very very special and there is very few oils that can go in it. Best of all, no 100% synthetic with such a low viscosity is available! The last I may try is ATF because this is the only oil with a lower viscosity............but it is even thinner when hot too and it lacks the additive package of a GL5.

I would have thought that a MoS2 additive would stick to metal and act as a lubricant for the time the oil is sufficiently thinner to reach any part of the gearbox when it is cold. But yes maybe it's not very good for the synchros althought a lot of people are using these kind of additive on manual synchrnized gearboxes without problems.

 

[Motorbike]

Pick a gear oil


or
OEM Supplier

 

[kilou]

quote:

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Originally posted by Motorbike:
Pick a gear oil


or
OEM Supplier

---

Thanks for the links Motorbike. I yet have TransElf TRJ in my box and this is the "best" Elf oil for my application. I've checked Statoil and they do not have any 75W80 oils. They only have 75W90 or 80W90. Their "thinnest" 75W90 have twice the viscosity of the TransElf TRJ at 40°C!!!!! So I would not try these Staoil oils. All I need to find is a manual transmission API-GL5 oil (but with inactive EP additives because my gearbox has brass synchronizer rings) with a cinematic viscosity lower than 47cSt at 40°C! I have not seen any other oil than TransElf TRJ with such a low viscosity at 40°C and this is really what I need. On the other hand, I must not go below 8.5cSt at 100°C otherwise the oil will be too thin.

In summary, only the viscosity at 40°C is important for me. It must be below 47cSt and be a API-GL5 oil with inactive EP additives. The "hot" index can be either 80 or 90, this is not important.