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[Brabs]

Well, as my 1.1 Passion is now over 11 years old, and has done just over 80,000 miles I thought that a gearbox oil refresh was in order. Although this doesn't seem to be listed as a service item I thought that as I intend to keep the car for some considerable time it couldn't do any harm. Draining was easy, after moving the stay bar but the refill plug is a bit of a PITA. Still, a bit of tubing weaving down through the engine bay did the trick. The old oil didn't seem too bad but and I know that there is the potential placebo effect, the change does see a tad smoother. 😏

[mr singh]

nice to see you used genuine stuff from Mercedes

[Brabs]

I know, I know... and some will possibly say that I could have got a cheaper alternative, which may well have done the job... but once every 10 years or so eh? 

[mr singh]

Cheaper to buy genuine as you know its the right stuff and grade for what you need

[Deszus]

I have to do the same oil changing with my manual 1.5 CDi. Drain plug is on the bottom of gearbox and fill plug is on the top? I have been oiling shifter steel links few days ago and think I saw something like steel plug there.

[Brabs]

Oil filler is not at the top as it is a measure of the level as well. It's about half way up... ish.

[Deszus]

Would it be easier to remove battery/airbox and access it from the top? I can see in the picture you haven't removed battery.
Any advice how drain off all oil from gearbox? I guess to put in exactly as much as was pulled out of gearbox.

What's more. There's lots of info about adding tiny bit of that oil to gearbox, which should helps reducing friction in gearbox. Any advice, any info, idea about product?

[Brabs]

Well, I wouldn't add any additives to the oil. Thing is... yes you want to reduce friction by a certain amount... but the synchro rings need a certain amount of friction to function. Just put in what the manufacturer recommends. Why should we presume to know better. They spend millions on R&D after all. 

[Deszus]

I'm not car mechanic and know rather just little about engines and manual transmission. Been talking with few really professional mechanics today and every of them recommend adding something to diesel tank. There is no fluid that can reduce friction dramatically when there is already high quality synthetic oil on parts A and B.

My problem is... Manufacturing is about making money. Engineering is about increasing probability of event so it is closest to 1. Sometimes those two things just don't connect at very end.

[mr singh]

I did use some of thet liquimoly gear box aditive in my SB3. Couldn't notice any different untill i replace the oil again when i replaced the clutch. It feels less smooth than before when it had the gear oil aditive

[Deszus]

MOTUL GEAR 300 75W-90 is perfect for gearbox and this is what I use in mine. Plus not long ago added 50mL of Ceratec to gearbox. It works smooth as silk.

Whatever there was inside gearbox, was nasty. That oil was just black and stinked much different than fresh gearbox oil. Too many black bits in it.
It's best to replace gearbox oil in 30-40kkm intervals or about every 25k miles. It's completely nonse to not do that.  It is as easy as engine oil replacement. I am gonna do it every third engine oil replacement (25k miles). Asked too many highly experienced mechanics. They all told me it's stupid not change gearbox oil at all and minimum interval is 50kkm...

Remember there is no filter for gearbox oil like for engine oil. All sh#t flows there freely.

[Alex]

There are several key differences between gearbox and engine lubrication that allow much more extended drain intervals in gearbox applications.

For one thing, the gearbox is sealed and no combustion occurs, thus no combustion contaminants reach the oil, and there's also no dilution from excess fuel enrichment. Additives (and the function they provide) also differ, and lubrication is not provided by oil pressure, the oil slushes around as the gears turn inside the gearbox partly submerged and they pick up oil with each rotation.

Engines need an oil filter because tolerances are smaller, you have tight passage ways and oil is under pressure. Combustion leftovers also contaminate the oil and make it turn acidic, in turn depleting your base reserves.

While i agree that never changing your gearbox oil can't be good, Mercedes did not specify it's good for the whole service life in vain.

I've changed my gearbox oil because i had a weeping driveshaft seal and when i changed that i refreshed the oil. I'll also change it again when i replace the clutch, but at 245.000kms the original one is still ok so it'll have to wait.

Changing it at set intervals would be a bit of a waste for me, oil is not a renewable resource and neither is my time

[CrazyG]

I have to agree 100% with all that you said there Alex 

[Deszus]

Small different sizes steel particles that I've found in my oil are acummulating in every gearbox. Thanks to friction, you don't need to grind every gear day by day.

If you're happy that steel bits are eating your gears and bearings I am pleased with that. Every good mechanic told me that not changing gearbox oil every 50kkm or more often is just stupid.
Gearbox oil gets hot thanks to friction. Gearbox oil lost it's viscosity because getting hot and cold again, again and again.
What's most funny is fact, that gearbox oil level needs topping up so level must be checked periodically. Ans those steel particles from sychro rings. Yea, what for changing gearbox oil.

So called by manufacturers 'Stands for lifetime of vehicle' means guarantee time. Manufacturer don't care about anything else. They care about selling next new car.

LOL, gearbox oil is CHEAP, why not even top it up? FORFOUR gearbox volume is about 2.2L. After warming up I drained 1.6L.

Ans this is my gearbox oil after 12 years and 100k miles. With TONS of steel bits in it. Enjoy what's in your gearbox. Viscosity of water.

[BlackCDI]

Which gearbox oil to buy for the getrag 5 speed in diesel and how many liters?