Why do people feel better with Slick50 in tranny?

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430
Location
Switzerland
Hi, I'm interested in the topic of manual transmission fluid additive and I've looked at several options like moly based additives, teflon based (PTFE) and some other as well. Thanks to this forum, I learned that: 1: reducing friction in a synchronized gearbox was not very good since synchro required friction to work efficiently 2: moly powder, carbon powder or teflon are all useless and not recommended as additive in a manual transmission. Yet I keep on reading very good reviews from people that tried Slick50, a teflon based gearoil additive for instance. They notably say that the box feel a lot smoother and gearshift are a delight with the additive. Unless all these people work for Slick50, this product must really have a beneficial impact on gearbox no? Why would this Slick50 be a snake oil as often found here?
 
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723
Location
Lower Alabama
The problem with additives (and we see this often here at BITOG) is that the user frequently experiences a placebo effect. Basically, they start paying attention to things they never noticed before because they need to justify their squandering of $50. Anecdotal evidence is NOT evidence.
 
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7,430
Location
beaver land EH?
kilou- Aside from placebo effect RE: slikk50s, there's absolutely 0 benefits when you put something like "powdered PTFE" additives into your M/T gearbox. Just like ATF, M/T gear oil for use in synchromeshed gear box must contain the following properties: they are designed to contain just the right amount of friction modifier additives to provide proper wear protection between gear teeths and bearings, and yet not enough to upset the proper synchromesh engagements (synchromesh cones require proper friction to sync up with the gear speed for smooth gear shifting/engagement). For notchy synchromeshed gearbox, sometimes by playing with various different brands/blends of M/T gear oil would helps in minimising that "notchy" feeling by finding the proper combination of "friction". For those synchromeshed gearbox that is working fine or new, you should make any changes to the type of gearoil used so as to upset that delicate balance of "friction" for proper synchro engagement. Bottomline: always try various different blends or brends of factory recommended MT gearoil fill until you find the magic combination and then stay with it. Don't bother with "so-called" friction modifying gearbox additives for they are just "placebo" effect.
 

kilou

Thread starter
Messages
430
Location
Switzerland
I understand you guys and mostly agree with you but I read and hear lots of people with grinding gears that could be "cured" with gearoil additive supposed to reduce friction. The placebo effect is a fact but when it comes to having grinds or not, it shouldn't be that much of a placebo. It's true that in theory nothing plays in favor of reducing friction on synchromesh but in practical life I don't understand why some people have seen dramatic results that definitely cannot be attributed to a placebo effect. Grinding vs not grinding is quite different IMHO. Is there really no possibility that these additive may actually work???
 
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723
Location
Lower Alabama
It depends on what you mean by "work." If you're using factory-spec'd fluids and getting grinding noises, then there's something mechanically wrong in either the clutch or the tranny itself. It is entirely possible that these additives are simply masking the problem... but at what cost?
 
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