Manual gearbox additive

[M104]

What's your opinion on manual gearbox additives ? I've always been reluctent to use an additive of any kind because i always thought oils are fully formulated products.

A very popular one here is Mecacyl HY. Claims it improves shifting smoothness and a lot of people say it does.

https://www.mecacyl.com/en/cars/2-hy-3760011060093.html

 

[Lubener]

In a properly working gearbox and using the recommended lubricant, no additives should be needed.

 

[M104]

That's also what i think but i've heard so much talk about this product making shifting smoother in most transmissions that i'm intrigued.

 

[Knerml12]

If you want to improve shift, use Red Line.

 

[Lubener]

That's also what i think but i've heard so much talk about this product making shifting smoother in most transmissions that i'm intrigued.

Try it and let us know how it works for you.

 

[MolaKule]

So it's good for any of these systems, anywhere in the world?

Hyper-Lubricant - Special Manual or Sequential Transmissions - Axles - Assisted Steering - Hydraulic Systems

Mécacyl is guaranteed for all mechanical applications anywhere in the world.

 

[benjy]

Redline quality Ester lubes work, but the $$$ keeps people from trying it!!

 

[M104]

Another product people use here is Mecarun P18, which is the same as Militec apparently. Many say it will make a notchy gearbox smoother but i'm still reluctant. What i'd like to try is Redline but just like the additives, i don't know if i want to spend 50€ for two quarts of fluid.

 

[Kamele0N]

If it is "notchy" try to change its gearbox oil with fresh one of proper viscosity & specs...

Maybe it has notchy shifting simply because it needs an oil change....

Because of the milage&age viscosity can fall out...

 

[Popsy]

Forget it. These Mercedes Gearboxes will never be Getrag (and not all Getrag are equal, either).
If there is a Motul Gear 300 that fits the recommended application, try it (online not too expensive). Was the best for cold "feel" for me, but warm there isn't much to do.

I've been recommended the mecacyl too...but never tried. Thought that would be some sort of moly additive, suspended in some dubious stuff. I've changed oil in gearboxes and found someblack moly (?) deposits at the bottom (maybe they get suspended when the car is running?).

 

[M104]

Shifting from 1st to 2nd always feels notchy as hell and you kinda have to wait for the proper moment, not to soon, not too late or it won't engage. If i am careful enough i can shift smoothly buy slightly keeping my foot on the gas pedal. Other gears are perfectly smooth, even downshifting from 3rd to 2nd. I currently have an oil from the dealer, MB 235.10, 75W, GL4 and it appears to be the best i tried so far with an ATF in second position. The worst was an approved 75W80 GL4/5 so i don't care about approvals in that case. These are the three fluids i tried so far. My last hope was Redline or some kind of additive.

 

[Le_bow_ski]

Motorcraft Full Synthetic Manual Transmission Fluid Part Number XT-M5-QS is expensive, german, has Friction Modifiers in it and is a favorite for the Miata transmission along with Redline MT90. I would imagine either of these well engineered and carefully formulated lubricants would perform better than some one size fits all additive that claims to be, “guaranteed for all mechanical applications anywhere in the world.”

 

[M104]

It seems like the best option would be to stick to the dealer fluid and not pour some dubious stuff in there !

 

[ollie]

Here was my findings. My NV3500 always was hard to shift and put into gear. I flushed the slave, replaced the fluid and it was still the same.

I recently had my engines real main seal replaced and had the clutch done as well (since trans was pulled anyway). It ended up being the darn throw out bearing. The spooky thing about it was there was not any kind of strange noise to indicate it was bad. The clutch, flywheel, and pressure plate were just worn normally for an over 132,000 mile truck.

In all my years of driving stick shifts I have not had a throw out bearing wear out before the clutch. According to my mechanic this is very common with the GM trucks. Good info to know.

Now my truck shifts better than when I got it at around 58,000 miles. Smooth as butter and drops right into gear. I also had the slave cylinder replaced. This was my call since it's behind the bell housing. It would be a shame to do all that work and pull the transmission for a slave cylinder.

 

[Popsy]

The clutch master/slave cylinders (if hydraulically actuated) is also an option to consider when 1st is hard to engage. If it's not a sealed system, I'd recommend bleeding/flushing with fresh fluid. On most cars it's shared with the brake fluid reservoir, but I don't know the specifics of yours.

 

[ollie]

Mine is a separate system. I bled and flushed it more than once. If you could have only seen the throwout bearing. It was ready to let go at anytime.