Desert Rider

What is the ZF 6-Speed Fluid recommendation? I had heard Castrol 10W60 for BMW's but have also seen comments that it's not recommended. Thx

dizwiz24

its fools gold

i dont care what some website claims, but BMW castrol 10w-60 belongs in bmw engines and not in transmission

I believe this bogus recommendation came about when the gm factory fill (thats in your owners manual) became discontinued and somebody discovered you could at least ‘drive the car’ on this fluid, but not drive the car well (ie. WOT upshifts) on it

once the syncromesh fluids (GM, Amsoil, etc.) became available, this outdated use-it-in-a-pinch advice remained out there (for some reason) to confuse newer members

ZWILDZR1

For your reading pleasure . Go to the zr1 specialist website . Under heading of presentations click on zf 40 section . Marc outlines the original part number Texico fill what it was changed to around 96 to the RS 10w60 to the TWS fill and then to the Edge fill around 2014 . ZF changed it several times over the years . Marc uses Amsoil MTF or Redline MTL or for single mass flywheel the Redline Heavy Shok Proof .

It's a good read . Another source is found on zf doc website by Bill Boudreau who rebuilds and blue prints the ZF 6 speed . You can find what he says under his FAQ or frequently Asked Question section.

dizwiz24

all that is great, but I cant deny the miserable experience I had switching to this crap in 2004? time period

I got the castrol tws 10w-60 from a bmw dealer.

the shifter felt notchy, the lever was harder to move, esp when cold. I took the car to the dragstrip and had to abort 2 runs because the gearshift lever physically wouldnt move into the next higher gear at high rpm’s.

I consulted with zfdoc, he suggested bad synchros and a rebuild at a cost of several thousand dollars

I drained the castrol and noticed the fluid full of bronze flecks. I put amsoil syncromesh in and immediatelty got full function back of my transmission. Ive since drained the fluid 2x and noticed no bronze flecks being generated when using amsoil syncromesh

this was on a 1993 with bluetag transmission, remanufactured for GM . The same trans that came in the car when i bought it with 26k miles in 1993. Now I have 92k miles on this trans.Ive had the lightweight alum fidanza flywheel on it since 2002


i almost wonder if the few people who have had good luck used castrol rs 10w-60 (was there an rs version?)

anyways if there was an rs version, i feel its unobtanium now and the crappy tws is the only kind you can get.

if you want a miserable experience, and possibly ruin your trans, dont listen to me and put it in

you wouldnt put transmission oil in your bmw engine so why put motor oil in your transmission? (Use manual trans fluid: gm syncromesh and amsoil syncromesh)

Desert Rider

Actually I'm looking for real world experience. Thank you!

dizwiz24

thanks. Ive been called all kinds of names here for providing the feedback i did. Ive posted that same response many times over the past 15 yrs

My trans had such a bad reaction to that stuff (it was shifting fine on whatever was inthere when i bought the car in 2001 with 26k)

i do find it ‘odd’ that my 1993 (supposed to be blacktag) had a blue tag remanufactured in it when i bought it btw

zfdoc is a dedicated guy who has been very helpful to me over the years. I cant explain why his site’s endorsement of the castrol 10w-60 just doesnt work in my zf blue tag on my 1993

Early on (in 2003), there was some praise for the bmw stuff (shifts smoother, etc) and thats why i tried it

but later on, 90% of the comments were negative on using the bmw 10w-60 castrol stuff. Though i seem to be the one screamimg the loudest against its use

good luck!

93Blackrose

I've used Amsoil Synchromesh in the past and it provided OK but not great shift smoothness in my 93 ZF (black tag). Many use Amsoil with great results but I ended up draining it after approximately 5000 miles and it drained like water (cold). The Amsoil fluid is relatively thin new but I was concerned how water-like thin it drained after only 5000 miles. I decided to try Pennzoil Synchromesh and from my experience, it provided noticeable smoother shifts than Amsoil.

RWDsmoke

Pennzoil Synchromesh worked ok for me if I changed it at least one a year. I went to Redline MTL about five years ago and I'm very happy with it. I think any quality synthetic syncromesh fluid would be good.

TravisSchoech

Synchromesh works great. Bang shifting at 6800, granny shifting at 2k, doesn't matter. My ZF and several I've worked on seem to love it.

arbee

Same reason I guess that Dodge and GM tell you to put automatic transmission oil in the NV 4500 5 speed.

sflier

I use GM 88900333 Synchromesh Manual Trans Fluid which is the correct GM fluid for our ZF (replaces 1052931, 12345349). It's 75W-80 which is about equivalent to 30W motor oil. It's not expensive, is OEM correct and works perfectly.

Gasnmyveins

That's good to know. It's even in stock, if you don't mind ordering online.

ZWILDZR1

I think you will find some who had issue with at least several of the fills mentioned. I was running the RL heavy shock proof in my first modified 91 . After doing a holeshot it developed a high pitch whine . It went away but the damage was done . After that it would occasionally pop out of first under light acceleration. I ended up replacing it with a new blue label ZF . I still have the old transmission. I drove it for over a year before replacing . Due to poor oiling it might have welded the reverse gear to the main shaft .

My current car has a single mass flywheel . I need to change the fluid. Not sure what Marc used in it . Could be the Amsoil, RL MTL or Heavy Shock Proof . If you have been using a particular fill and not having issue than keep doing what your doing .

Purple92

I've used Redline MTL. Seems to have worked fine so far.

russlg6584

i just bought some of this and was concerned because it said on a data sheet that it is a supercession for 1052931 which was a 5W30 trans oil. All the pictures showed the bottle without a weight listed and one website claimed it was 5W30. I got the three bottles delivered today from my vendor (AC Delco warehouse) and it says 75W80 right on it. After hearing the horrors of 10W60 and some not liking the Amsoil I may give this stuff a shot and see how it goes.

Gasnmyveins

That weight is for the differential. It's vastly different from what you need for your trans. It probably has the friction modifiers that the diff needs, as well. This could be very harmful to run in your transmission. And that trans... it ain't cheap.

car addict

Have been using this for a couple years. Works fine for me.

Bill Chase

Amsoil Synchromesh, per email exchange with zfdoc, as well as others that use the zf s6-40 behind 500+ rwhp boosted c4. The gm Synchromesh is ok according to the same people, but the price difference is insignificant, local dealership didn't have the Synchromesh, but amsoil dealer had the Synchromesh, so that's what I used. Zero issues on a 107k black tag behind 450+ fwhp.

russlg6584

I opened the bottle and it is definitely NOT rear diff fluid or rear diff gear oil. Those oils stink to high heaven, this smells like motor oil and when touching it feels like 5 or 10 w30... The bottles I bought must be older stock because the label says 75W80, pic attached. I'm going to use it. If I had an amsoil dealer nearby I'd go and have a look, sniff and feel of their 5W30 synchromesh.

rocco16

Ran the Castrol/BMW engine oil for many years, and suffered from really notchy shifting.
Changed to Amsoil Synchromesh in 2019 and the shifting is MUCH smoother.
Highly recommend.