Manual transmission difficult after drain and fill: CV joint grease to the rescue! What's the science behind it?

[Superflan]

Which vehicle, the Peugeot or the Suzuki?

Usually Peugeot or Renault cars, specified for 75W80 GL4 gearbox oils.

It may very well be short with Moly in there - the synchronizers may not work, they could slide instead of gripping and changing shaft speeds - and while it might feel smoother initially, I can see this causing gear wear and early failure.

Awfully risky.

Yeah, usually it was after fixes where we wouldn't put back the old oil in. Usually, if we put back the old oil in, there's no issue. New oil and never drained transmission with 150000+km on it: issues pretty much guaranteed. New oil in a transmission that has been flushed at 60000km: it would be okay. When there's an issue, either we put back some of the old oil into the transmission, or put CV grease and call it a day. It would run fine for at least 2 years, and at this point those cars are needing major repairs and will go to scrap.

With most MTF's, moly will compete with the friction modifier in the formulation and result in synchronizer slippage so it is not a good practice.

What specific oil did you add and what was its viscosity?

That's really interesting Generally we use Total Gear8 75W80, GL4 and PSA approved. Believed to be the factory fill.

Yes, quite a few are these days. You're only supposed to change the fluid after a cllutch change or other work on the transmission.

Like, every french manual transmission cars are filled for life, and a lot of Euro too.

 

[Jetronic]

Like, every french manual transmission cars are filled for life, and a lot of Euro too.

The reasoning being: it's possible you introduce dirt during refill and that's much worse than running an older fluid with wear materials.

 

[Superflan]

The reasoning being: it's possible you introduce dirt during refill and that's much worse than running an older fluid with wear materials.

I heard something about motor oil developing protection after the initial oil wear period. is there such possibility with gearbox oil?

 

[Fabulous50s]

I heard something about motor oil developing protection after the initial oil wear period. is there such possibility with gearbox oil?

The reasoning being: it's possible you introduce dirt during refill and that's much worse than running an older fluid with wear materials.

Yeah, that's why I never change me engine oil after the initial break in..... The French said I'd get dirt in it....

 

[IndyIan]

Usually Peugeot or Renault cars, specified for 75W80 GL4 gearbox oils.


Yeah, usually it was after fixes where we wouldn't put back the old oil in. Usually, if we put back the old oil in, there's no issue. New oil and never drained transmission with 150000+km on it: issues pretty much guaranteed. New oil in a transmission that has been flushed at 60000km: it would be okay. When there's an issue, either we put back some of the old oil into the transmission, or put CV grease and call it a day. It would run fine for at least 2 years, and at this point those cars are needing major repairs and will go to scrap.


That's really interesting Generally we use Total Gear8 75W80, GL4 and PSA approved. Believed to be the factory fill.


Like, every french manual transmission cars are filled for life, and a lot of Euro too.

I don't know how old the trans fluid was in my Focus, but I changed it at ~220,000km, and it was dark. I put in new ford trans fluid and nothing changed in shifting, so I think its transmission dependent.

 

[Jetronic]

Yeah, that's why I never change me engine oil after the initial break in..... The French said I'd get dirt in it....

They don't say not to change motor oil. And in practice you're going ta have one clutch change anyway.

 

[MolaKule]

Yeah, usually it was after fixes where we wouldn't put back the old oil in. Usually, if we put back the old oil in, there's no issue. New oil and never drained transmission with 150000+km on it: issues pretty much guaranteed. New oil in a transmission that has been flushed at 60000km: it would be okay. When there's an issue, either we put back some of the old oil into the transmission, or put CV grease and call it a day. It would run fine for at least 2 years, and at this point those cars are needing major repairs and will go to scrap.

Why would you put sheared-down, dirty oil back in any type of transmission?

I have to say, this makes no sense whatsoever.

 

[Superflan]

Why would you put sheared-down, dirty oil back in any type of transmission?

I have to say, this makes no sense whatsoever.

before those experiences I wouldn't, but when I needed, in those fill-for-life transmissions, i would partially remove half a quart of new oil, put half a quart of old oil (filtered using a simple strainer if I'm not sure of grit or dirt falling in the drain pan) back in and the difficult shifting would stop. this, or CV joint if for example a leak made the gearbox almost empty.