oscarm98

I know there was a thread (and I read it) a while ago about which oil to use.

It seems that Castrol has since changed the name of the Trans fluid Gear Oil for the ZF 6-40. The manual and ZF recommend the Castrol RS 10W60 "Engine Oil" I was only able to find the Supercar oil online I emailed them yesterday and this is the response I received:

"Castrol RS 10W-60 is a discontinued product. Castrol EDGE Supercar 10W-60 meets the same specifications and can be used with confidence in your application. Thank you again for contacting Castrol, we value your patronage!"

I assume that "same specifications" means that it works in our transmissions with no problem?

Barrier

Hi, That is the same oil that was recommended by ZF as well as one of the US experts on the Transmission ZF DR.
There are other Fluids that can be used. Do a search and you will get many suggestions.
I am using the Castrol now I most likely will try the Amsoil next time for no reason other than I want to. I really think any of the Fluids will work just fine.
The Transmission is very strong, I believe it was first designed for HD Truck usage.It has been reported that it is a noisy which is why GM used the Dual mass Flywheel in our cars, which BTW is no longer
manufactured. Cars were delivered with GM spec fluid which has since been replaced.
I honestly do not know if any ZF failures have have been attributed solely to the use of any of the approved fluids no matter which Brand.
Barrier

oscarm98

Funny that you mentioned the "noisy transmission" because that is exactly why I drained mine. It sounds like marbles getting mashed up in there with the clutch out, engine in neutral. The noise goes away when I push the clutch in???

I started to pull it out of the car because I thought it was going to Grenade.

I have since talked with the ZF USA rep (maybe the same helpful guy ) He said that since it is not making noise while under load (driving with the clutch out) and not having trouble shifting to NOT pull it to rebuild it YET (especially since Rockland Gear wanted more than $5k to do it)

I already have it halfway out so I am going to go ahead and pull it to check the clutch and the Throwout bearing just in case that is the reason it is making noise.

Anybody have the same experience?

Oscar

phDiesel

Not sure how long you've had the car but that noise your describing sounds like the one that's made when a car had been converted to single mass almost to the T.

dizwiz24

The castrol crap is motor oil for your bmw engine - not transmission oil.

im not sure what you manual you spec of. My 93's manual recommended a 5w-30 based transmission oil with a gm part number - now discontinued.

the gm replacement is gm syncromesh fluid. I have alao had good luck with amsoil syncromesh.

i had terrible luck with this castrol 10w-60 engine oil. Shifts became notchy - esp when cold. The gearshift lever would jam and not even allow you to engage 2nd at wot from 1st. Sometimes you could force it and get a grind.

Zfdoc told me my clutch hydraulics were prob bad, so i replaced them with nos oem parts (still available back in 02), the grind and notchiness was still there. He then suggested my synchros were shot and i needed a rebuild at a cost of thousands.

i switched back to gm syncromesh and the problems instantly went away. The used castrol oil was full of copper flecks indicating excessive wear occurring to the synchros.

zfdoc has some good advice butl his website is extremely old. Parts and stuff he discusses on it are no longer available or not the same as they used to be. Imho the castrol stuff falls into this category.

you are not doing your transmission a favor with this stuff.

dizwiz24

Noisy transmission, on a blue tag, is a result of countershaft play in the transmission.

It doesnt come from the flywheel like a lot of people here think it does. The flywheel dampens it. Afternarket single mass flywheels dont do as good of a job as the dual mass did.

Zfdoc has some good advice about trimming the transmission with A thicker washer to take up slack.

this is a common problem with other manual transmissions. Not just zf6

black tag zfs are noisier due to straight cut gears - i dont have any info if the countershaft mod works on those ones too.

good luck !

Christi@n

Hi better to use amsoil synchromesh, that is more lighter than castrol

Kubs

I run AMSOIL in my race car and I have smooth shifts every time. I change it annually since it sees some heavy use and I have never had flakes or anything come out with the fluid. It always looks good still.

https://www.amsoil.com/shop/by-produ...30/?zo=1934716




What Castrol means by meets the same specs is that standards set in place by the engine manufacturer are met for engine oil (BMW LL1 LL0, Chevy Dexos 1, etc.). This does not mean it will work in the ZF. Engine oil and gear oil are built on different additive platforms. Just because an oil is similar in weight does not mean it is made for the different alloys or different clearances in a different application. Get a fluid that was designed to work in a transmission.

GREGGPENN

Yes, the FW does dampen it. When the springs in the FW "fail", you have "floppy" counterweights in the FW -- in addition to the original problem. So, you can be hearing both.

thurman_merman

Another vote for amsoil synchromech. I have noticed it is much smoother than the 10-60 oil and zfdoc gave it the thumbs up when I asked him about correct oil for the zf6.

9T3VETTE

Someone remind me how many quarts the ZF6 takes...I'm going to order some amsoil.

Interestingly enough, a few years ago I found the correct factory fill fluid at a local Chevy dealer that was bought up. Ever since putting that fluid in I get a grind when shifting hard 3-4. Never remember that happening before.

Hopefully a fresh fluid change with a high quality fluid will fix it up.

Christi@n

You will be ok with 3qt... Anyway Zf s 6-40 takes just a little bit more than 2qt

oscarm98

2.2 Quarts to be exact...Just enough for someone to put 2 quarts in because they want to save $$.

Don't do it! Just suck it up and spend the extra $15 for the third quart, the trans costs $5,000+ to rebuild.

Reason: ZF is German, Germany uses Litres .......2.2 quarts = 2.0 Liters.

Buy 3 quarts.

Oscar