synthetic gear oil for 901 trans with ZF/LSD

[Bnut]

Cool site :-)

I'm thinking about changing the oil in my 901 gearbox sporting a ZF limited slip diff to synthetic. Interesting articale about Amsoil synthetic oils in the tech section but I don't know how it will react with the 901 style syncronizers or the LSD..Any opinions or experiences?

Thanks

[TimT]

I have Mobil1 in my 901 with lsd...

go for it..

[TimT]

Yikes I just realized I have 5 901 type boxes LOL

1 each in the 911 and 914.
a built spare for each,
and an extra case and enough gears to make a 10 speed LOL

[toman]

I put redline synthetic in my 901 (914) and it made a world of difference. I had used both Valvoline and castrol dino oils before. I have no idea if a LSD would make any difference though, sorry

[pwd72s]

Oh no...you MUST us Schwepco in all early gearboxes. Why? Because Bruce Anderson once said so, long ago... (BTW, I've been running synthetic in my 915 gearbox for about 5-6 years, and like it better than the schwepco I used to use.)

[speeder]

I had read somewhere along the line that synthetic is not ideal for Porsche-type synchros, (901,911,&915 boxes), but hey, if you guys say that it works good, I'll take that as the voice of experience.

Synthetic gear lube is great for gears w/o a doubt, just not enough friction for our synchros(?), or so they say.

[Wil Ferch]

Two things...
Make sure the gear lube is GL-5 rated. Most are GL-4, like most Redline ( hint, hint).
Second...although good for the box, synthetic might not make the baulk-ring syncros of the 901/915 boxes work well.
I've heard that a combo of GL-5 Redline with a small amount of "BG Syncroshift" ( ?)...or some other friction-modifying mineral oils...may work very well. On Rennlist, there is usually someone from Redline who occasionally brings up the magic concoction and posts that.

---Wil Ferch

[jluetjen]

I recently switched from Valvoline Durablend Synthetic 80-90 gear lube to Swepco in my 901 (without an LSD). The Swepco certainly helped the syncros work better and the car shifts easier now, especially on the 1-2 shift. Admittedly both the 2nd gear and 1st gear syncros on my car are on their last legs, but the Swepco certainly helped.

Now keep in mind that LSD's depend on friction to work. Changing from Swepco to something slicker quite possible could change the locking affect of the diff. Gear lube is cheap, I'd suggest that you try it and if you don't like it, you can switch back.

[Bnut]

Good input..Thanks for the help guy's

[Brad Roberts]

My 901 ZF's wear out 2 times faster with Redline in them (race cars) and we are sponsored by Redline with full engineering support. The boxes themselves wear out the sliders and synchro rings almost twice as fast as the box we use SWEPCO in.

The Porsche tranny engineers didnt have synthetics in their arsenal of engineering secrets back in 196X when they developed the 901 box. They specifically factored in the gear lube to help slow down the synchro's during engagement. Synthetic lubes dont help the pieces slow down and cause premature wear. The car will shift like gang busters for the first 800 miles or so.. then go down hill from there (over time)

I would imagine Bruce Anderson is one of only a hand full of people who has raced a 901 box at the 24 hour of Daytona (which is where you learn quickly what works and what doesnt).

My .02

B

[Zeke]

A hundred years ago some guy named Granatelli showed how you couldn't hold a socket between your fingers when dipped in STP. When I tore down my 901 that had Swepco in it....same thing. Couldn't hold on to anything. Swepco could care less if you use their product in your 901. When I talked to them, they told me that their target market is BIG machinery that uses lots of the stuff. This is hundreds of thousands of dollars worth of equipment that is being protected by Swepco. The amount that all of us Pcar guys use in a year doesn't even show up on the sales chart. We use it beacuse it works.