MoS2 in manual transmission

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Hi, I know this is a common question but for whatever reason the Search returns "no matches" when I look for MoS2 or Moly in this section. Well I know that most of you are against the use of MoS2 in a synchronized manual transmission since synchros need friction to work efficiently. Now many people who tried a MoS2 additive (made by Liqui Moly) in their georbox report good results so that I may want to try this additive. My main purpose is to protect my gearbox in the long run, not really to have lightning fast shifting abilities. So I'm asking if adding a MoS2 additive (sounds to be a plain MoS2 paste like additive) may cause any harm to the transmission or differential (FWD) unit. Also as I'm using a GL5 gearoil, is it possible to have a bad reaction between the gearoil+EP additive and the MoS2???? My view is that I should try the additive. If the shifting is bad as most people here would predict, I can drain the tranny and refill with fresh fluid (with an AutoRX cleaning in between for example). But I first want to make sure that it's not dangerous for the transmission to run a MoS2 additive. Does MoS2 turn corrosive in a transmission??? Would be glad to know your opinion about this (the Moly section on BITOG is quite encouraging no??). PS: the additive I'm looking at is "Liqui Moly MoS2 anti friction for Gears". In case you have a better choice let me know too. Thanks
 
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If you want your transmission to last, maintain it with quality fluids. Practice a reasonable change interval and don't bother with additives. What year/make/model?
 
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kilou- I've used MoS2 gear oil additives in my Mazda 5spd gear box in the past and while I like it, the "good times" are rather short-lived (typically 1/2~1yrs of regular daily driving). At the end of all these, you'll have to drain and refill your gear oil in order to rid of the residue. I do not detect any corrosion issues with using MoS2 (surprise?>) throughout the course of a 3 yr running of semi-synthetic GL4 75W90+MoS2 at all. After trying M0S2 for 3 yrs I decided to switch to full-syn (M1/Q-state) GL5 75W90 and never looked back since for it holds it's performance very well (3yrs between exchange) and it is smooth as semi-syn+MoS2. Conclusion. M0S2, even in suspended mode, is good only if you have some syncho (notchy)problems, or you are into "additives". In proper fashion, there shall not be any need for additives such as MoS2 under 90% operational circumstances. All other additives are strictly "marketing" so caveat emptor. 2c's worth
 
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Rather than put an additive in the gear oil I prefer to find the best gear oil for the application. I would try some gpIII and synthetic gear oils and see how they work. If you are primarily concerned with longevity and not shift quality, then an synthetic oil with a good EP add pack will work well. Regular changes are more important than the oil type in a manual gear box since most do not have filters or coolers.
 

kilou

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Thanks guys for your comments. I agree that using the best fluid is probably the right way. However in my case there is no such "best" fluid because my car calls for a 75W80 GL5 oil. There is NO 75W80 GL5 fully synthetic gearoils, either 75W90 GL5 or 75W80 GL4 can be found in synthetic (at least here in Europe). My car really calls for a GL5 and a 75W80 so I'm left with 2 or 3 possible gearoils that all are petroleum based or at best part synthetic. I'm now using the "best" oil which is the one specifically recommended by the manufacturer. This oil has the best cold flow abilities compared to others (lowest brookfield viscosity in the 75W range) and its EP additive pack is safe for brass synchronizers. If I could find a fully synthetic gearoil in the correct grade and with a GL5 rating, I would sure go that route first but it's not a possibility in my situation unfortunately. That's why I'm looking at MoS2 additive (or others). Thanks to this forum I must say that I would never put any oil additive (except AutoRX) in my engine. However the gearbox is another application which appears to be "safer". My main concerns are: - Does MoS2 (solid particles) becomes corrosive or abrasive in gearbox applications? (Quest tends to think it's not) - if the MoS2 particles fall on the bottom on the transmission, is there any problem with that? No oil paths? (my transmission doesn't have any filter too) - Is there a possible bad interaction between EP additives of the oil and MoS2 particles? - Any reaction between MoS2 and yellow metals?? - I read that any friction reducers (especially MoS2 and graphite) would overheat the synchros.....is this right? (I guess it's because synchros are spinning longer since the synchronization is supposed to be slower when friction is reduced...but it sounds weird). - Can I keep the same OCI with MoS2 added to the gearbox? - Last but not least: if I'm not happy with the results, does a drain with possibly AutoRX enables to remove ALL MoS2 in the gearbox or will it stick everywhere forever??? Quest your review is interesting. I want to use MoS2 especially because my gearbox is notchy. I also heard this kind of gearbox is prone to bearing failures so MoS2 should help them a bit. But what do you mean by "the good times" and what residue are you talking about? Did MoS2 produce residues in the tranny or are you speaking of normal wear particles that need to be drained out? And finally did you feel a real benefit with MoS2 added to your first gearoil (before you used synthetic)???
 

kilou

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Car is a 1997 Volvo S40 2.0L with 5spd gearbox (gearbox is built by Renault, a french car manufacturer). This car is not available on US market.
 
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Can you get Redline oils? If you are stuck with only a few oil selections, then maybe an aftermarket additive is your only choice. Regardless, practice reasonable change intervals. Every couple of years or 30k miles is enough for a gear oil. I've heard of no negatives with using MoS2. So, if the tranny shifts OK, continue to use it. If not, plan an earlier drain/refill. I don't see the need for a flush.
 

kilou

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I may get Redline imported but that would be extremely costly. Furthermore I already checked with one salesman and they have no 75W80 GL5 oil. Their MTL is a GL4 and their GL5 are 75W90. Moly is supposed to stick to metallic parts so I guess it would be a pain to remove if I'm not satisfied with the results. Do you think I can get most of it out of the gearbox simply by draining??? Also I read there may be some corrosion issue with MoS2 in presence of copper alloy bearings. Any idea about that?
 

kilou

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Redline does have a regular synthetic GL5 75w80 gear oil. It is called 'lightweight gear oil'. http://www.redlineoil.com/pdf/5.pdf Don't confuse the above with the 'shockproof' series. Superlight might be another option. http://www.redlineoil.com/whitePaper/11.pdf
You're right in a sense but don't forget that the Lightweight and Superlightweight oils from Redline are designed for differential units only and not intended to be used in a synchronised manual transmission. I already checked these options with Redline and they told me these oils (while complying to the required standard of my gearbox) should not be used in a synchronized tranny because they do not have the correct friction (they are far too slippery for synchros apparently). Aside of this major drawback it appears those oils would not be the best choice for my gearbox anyway. First the SuperLight is far too light at operating temp (I need a 80 grade which is twice thicker as this oil). Second while the Lightweight would be the right viscosity and the right EP additive level, it doesn't offer better specification than the gearoil I'm using right now which is a part synthetic oil (TransElf TRJ). In short the "cold" viscosity of the oil is 1/3 lower for the TRJ compared to the lightweight (45cSt vs 67cSt), the viscosity index of the TRJ is slightly better (but marginally, 175 vs 160) and the pour point is "only" 5°C lower for the Redline. All in all, despite being a semi synthetic the Elf gearoil remains better for cold properties compared to thisfully synthetic differential oil. Redline recommended only their 75W90NS GL5 which has special additive (NS=non slippery) to work in a manual transmission. However this oil is a 90 grade so it would shift terrible when cold if used in a gearbox requiring a 80 grade. At last, providing all these drawbacks for my particular application and considering the high cost of Redline oils in Europe (shipping charges are a rip off) it's better for me to stick to the manufacturer recommendation as far as oil is concerned and "experience" with additives also this idea is not the very best I agree. However the only risk I'm ready to take is to buy snake oil and loose some $$.....but I want the additive to be...at least...safe for the gearbox!
 

kilou

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Castrol TAF-X as sold in Europe, General Motors (Part #12346190) and Chrysler (Part #4637579)
The Castrol TAF-X is a 75W90, not a 75W80. Someone has already tried to pour in a very good 75W90 full synthetic (Motul Gear 300) in the same box as mine: shift was terrible, especially when cold due to the too thick oil. This is definitely not the solution and it's also not recommended by Redline too. It would be too nice it worked since a lot of synthetics are available in 75W90. I really wonder if the "all synthetic" is the solution anyway. I understand that a synthetic might be good in grade such as 75W90 or above since only synthetics may combine good cold properties and a thick oil film at operating temp. However when it comes to a 75W80 these requirements are less important since the "multigradity" of the oil is not that big. So any semi-synthetic is more than enough here probably...and this is certainly why there are not so much 75W80 full synthetics out there also the cars calling for this grade are more than common (especially in Europe). As for the GM and Chrysler proprietary fluids, I have no idea if they can be used since they have no GL rating as far as I know...but they probably correspond to a GL4 and not GL5 in term of EP additive. Really I do think that additives are probably the only way for me. I know Liqui Moly does 2 MoS2 gear oil additives: - Anti Friction Gear Oil additive (1014): it appears to be a fat grease type product to mix with oil. It sounds to be pretty thick as it is sold in grams and not ml.... - GearProtect (1007): supposed to be a superior version based on synthetic fluids. 4x more expensive than 1014! Which one should I go for? I'd personally try the cheap one...
 

kilou

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Is this correct????? "The commonly used additive of MoS2 (Molybdenum disulfide), in addition to having virtually no lasting emulsification in gear oil, can also have detrimental impacts. MoS2 oxidizes rapidly, producing MoO3 (Molybdenum trioxide) as a bi-product. MoO3 is hygroscopic. Once hydrated, the resultant bi-product is H2MoO4 (Molybdic acid) commonly used for etching metal. I'm not certain I want that in my gearbox" (http://www.morini.com.au/phpBB2/viewtopic.php?p=12921&sid=59799e17ef68bd9474592da8b4268701)
 
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TAF-X in the gm and chrysler part #'s are rated 75w85 and are all about cold temp duty in heavy duty transmissions. It's sold in the the US as syntorque LT and is quite expensive but good. Just an option to look at after you try the moly. ONly mentioned it because I thought it may be more readily available then some of the other specialty oils mentioned.
 
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Quote:
Is this correct????? "The commonly used additive of MoS2 (Molybdenum disulfide), in addition to having virtually no lasting emulsification in gear oil, can also have detrimental impacts. MoS2 oxidizes rapidly, producing MoO3 (Molybdenum trioxide) as a bi-product. MoO3 is hygroscopic. Once hydrated, the resultant bi-product is H2MoO4 (Molybdic acid) commonly used for etching metal. I'm not certain I want that in my gearbox" (http://www.morini.com.au/phpBB2/viewtopic.php?p=12921&sid=59799e17ef68bd9474592da8b4268701)
I'd say not really Moly will oxidize BUT as I remember about >700F if gear box is that hot you have a problem. That info is more correct for high temp bearing/open chain use not gear box. bruce
 
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Also Moly disulfide the powder has been used for years in gear box power transmission with no problems use about 5% bye wt. Maybe wrong but I also think is non corrosive to yellow metals. bruce
 

kilou

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ELF HTX 732. 75W-80, GL5, full synthetic gear oil (with moly ) www.lubadmin.com/upload/produit/FichePDF/lang_1/573.pdf
Right but again this oil (although being a 75W80) is thicker when cold compared to my current oil. For example the HTX is 30% thicker at 40°C than my oil (68cSt vs 47cSt at 40°C) which is not what ou want for cold shiftability. Moreover...well...this is a racing gearbox oil, hard to find.....and it cost 118Euros for 5liters which is about 112US$ per gallon!!!!!!! I love my gearbox but....
 
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From personal experience I would say DO NOT USE Moly in a synchronized tranny. Had a customer about a year ago buy 2 - 55 gallon drums of Texas Refinery Corp. Moly universal gear lubricant for use in his dump truck transmissions and rear axles. Great stuff for those applications and for in Eaton Road Ranger non sychronized transmissions. However, he asked me if I thought it would work in his International 4700 box truck with Spicer 6+ transmission which is synchronized. My answer was a big NO. To make a long story short he did not listen to me and changed the fluid out and installed the Moly gear oil, big mistake. The transmission clashed gears something fierce after that. The only thing I could figure was because it (how should I put this) over lubricated the synchronizers and did not allow them to grip properly when shifting gears. He drained and refilled with the proper 50W synthetic gear oil and the problems went away within 3 or 4 day's. Simply put I would not suggest any Moly, Graphite or Teflon solid film lubricant oil or additive in a synchronized transmission application.
 
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