Best Transmission oil for improved synchro performance

[fernando306]

Hello my friends,

I'd like to change the oil on my 6-speed manual transmission. It's quite notchy first and second, and at 86k miles, I doubt that the oil has ever been changed. What would be a good choice to help out those synchros? I bet they're a bit worn out, not too terribly I hope.

It's overwhelming the many choices, from mineral to synthetic and additives. So I figured I better ask!

Thank you so much.

 

[markplant]

The change from 1st to 2nd is well noted as been notchy , oil change will help , also have a look at clutch delay valve CDV as a lot of people remove this

 

[fernando306]

The change from 1st to 2nd is well noted as been notchy , oil change will help , also have a look at clutch delay valve CDV as a lot of people remove this

Exactly my friend. I never knew about it, just watched some YT videos on it today.

Which Gearbox oil is best in your experience?
ACDelco 10-4014 Friction Modified Synchromesh Manual Transmission Fluid
Valvoline Syncromesh Manual Transmission Fluid
Amsoil Manual Synchromesh Transmission Fluid

Any other suggestions?

 

[markplant]

Mine was fun summer of this year along with the diff , unsure which brand was used , as long as in spec , clean will be better than 16year old oil in my case, many use millers.co.uk or call Opie oils

 

[Thrustyjust]

I used Valvoline on mine . Oil wasnt too bad looking, but suspect it has never been changed looking at the unmarked drain and fill plugs. Still notchy first and second , but does get better after it warms up.

 

[colb]

Make sure the filler plugs come undone before draining the gearbox and Diff, they have been in there for a long time, changing their contents is a good move nothing lasts forever despite what BMW would have you believe with their fill for life description. Check what you need with Opie Oils, usually decent prices. When changing mine on the Z3 and Z4 I found it easier to run a plastic tube down to the gearbox filler plug through the engine bay and let gravity fill it from above. Same method for the Diff using a tube from the boot. The drain plug for the diff can be tricky to get a hex key into as its on an angle, a short hex key worked for me. Also make sure you have new sealing washers for the Diff drain and filler plugs, they are alloy and you will find they will have corroded into lace when you get the plugs off. Gearbox are tapered threaded so don't use washers.

 

[Jfgoldfish]

I used redline (MT90 I think) in mine.
It is still quite notchy when cold but smooth as silk when warm.
Some folks mix 50:50, MT90 to D4 ATF. Both redline products. Apparently that concoction works very well!

I don't work for redline btw! I'm sure many other quality oils will perform as well, or better than redlines offerings.

 

[TheDan]

I used redline (MT90 I think) in mine.
It is still quite notchy when cold but smooth as silk when warm.
Some folks mix 50:50, MT90 to D4 ATF. Both redline products. Apparently that concoction works very well!

I don't work for redline btw! I'm sure many other quality oils will perform as well, or better than redlines offerings.

Advocate for Redline also. Not tried the mix method, will definitely be giving that a go next time!

 

[Thrustyjust]

Make sure the filler plugs come undone before draining the gearbox and Diff, they have been in there for a long time, changing their contents is a good move nothing lasts forever despite what BMW would have you believe with their fill for life description. Check what you need with Opie Oils, usually decent prices. When changing mine on the Z3 and Z4 I found it easier to run a plastic tube down to the gearbox filler plug through the engine bay and let gravity fill it from above. Same method for the Diff using a tube from the boot. The drain plug for the diff can be tricky to get a hex key into as its on an angle, a short hex key worked for me. Also make sure you have new sealing washers for the Diff drain and filler plugs, they are alloy and you will find they will have corroded into lace when you get the plugs off. Gearbox are tapered threaded so don't use washers.

I use 'ketchup ' pumps off ebay for about a fiver. Easy to pump in as designed for thick liquids, but easier if warmed and can do a gearbox in 5 mins. I bought a few and then use it in reverse with a piece of tube for the diff , as dont have a drain plug on the diff, just a fill one. Then you dont contaminate clean oil with dirty oil. The diff oil was pretty mucky when it came out. Both oils done 60k miles.
The ketchup pumps need the pipe cut to length for 1 litre bottle for the gear oil, as ketchup is usually 5 litre tubs. Works a treat.

 

[Chris_D]

i never use 2nd gear 8)

 

[tug]

i never use 2nd gear 8)

I bet you do. Go on admit it. Ya do doe dontcha doe..... oke: :lol:

 

[Chris_D]

i never use 2nd gear 8)

I bet you do. Go on admit it. Ya do doe dontcha doe..... oke: :lol:

Never. They can tear me fingernails out but I’ll never use 2nd gear. Never I tell you!
:lol:

Seriously though, I’ve been skipping 2nd and 4th for years now especially from cold and if I’ve been commuting in the zed.
Save a lot of money doing that, not blasting away from the red lights and coasting to red lights from miles away.
It irritates the Dutchies like you wouldn’t believe but increases your fuel economy exponentially.

 

[Natishin]

I talked to my mechanic about changing the transmission oil after winter storage and he indicated he brings in OEM oil for all his BMW clients. Feedback? Is there something better I should request?
2003 3.0i, Merlot.