Best Tranny Fluid?

Red96LT4 · 12-08-04, 10:29 AM

Can I get some recommendations for the best tranny fluid for a LT4 daily driver. I'm looking at the GM stock fluid, Castrol 10/60, or a RedLine product. Thanks.

Vettelt193 · 12-08-04, 10:50 AM

I hear the BMW castrol 10/60 is the best.

I have used Mobil 1 10-30 on past cars, as well as my current car... that is a huge improvement over stock. I hear red-line is good too, but more $$.

For me, I would rather change it more frequently and spend a bit less. From what I understand, the 10-60 is $9-$12 /liter. I get mobil 1 for half that, so I prefer to change it twice as often. On my next change, I will probably try 10-40 to see if there is any difference.

ßill · 12-08-04, 10:57 AM

I put redline "MTL" in mine about 2 weeks ago. So far I like it. The transmission seems quiter and shift easyer. I'v only put around 100 miles on the car since the change maybe someone with more knowlege will respond

Vettelt193 · 12-08-04, 03:23 PM

CAC member 96CERon pointed me to the ZFdoc website in a different thread...

over on ZFdoc they have some research on the 10/60, all positive stuff.... but, it also has a bit of a caveat that any fluid needs to be changed somewhat frequently (I think he says 15k over there) until someone comes up with a 'copper magnet' (LOL) because the copper particles get into the synchros.

I have yet to see a comparo on using a lower cost oil, like mobil 1 with more frequent changes Vs. using the more expensive 10/60

Tuna · 12-08-04, 05:38 PM

I've been using RedLine MTL in my 92 ZF6 for years. Can't complain. Much better than the factory fill.

Roadster Guy · 12-08-04, 09:51 PM

Quote:

Originally Posted by Red96LT4

Can I get some recommendations for the best tranny fluid for a LT4 daily driver. I'm looking at the GM stock fluid, Castrol 10/60, or a RedLine product. Thanks.

Castrol TWS 10-60 is what I put in last month. Very pleased. I had to get it at a BMW dealer as they seem to have the monopoly on it up here in the Great White north. My 6 speed was always pretty quiet and smooth but it seems even better now. ...but that could be all in the head. The book, 101 Projects you can do on your Corvette (1984-96) by Richard Newton recommends the Castrol 10-60. Whatever, I would think synthetic is the way to go.......and I agree with changing it on a regular basis.....ZF the manufacturer apparently recommends changing it about every 30,000 miles or so if I recall correctly from the same book. That is a huge difference from GM's lifetime fill position.

LT4BUD · 12-09-04, 09:52 PM

I went with the Castrol....smoothed out the shifting noticeably....replaced factory fill at about 30k miles..

wx briefer · 12-10-04, 09:54 AM

I agree, castrol tws 10-60 synthetic. Smooooooths it right out! You should be able to get it for around $8 at a local independent BMW service shop. You need 2.2 quarts so pick up 3.

96CERon · 12-14-04, 12:40 AM

Here is what ZF web site says:
Q: What type of oil do I need to use in my ZF S6-40 Corvette transmission?
A: ZF only recommends the following lubricant for S6-40 transmissions. The GM oil (available from GM with part number 1052931) and the Castrol Synthetic Formula RS 10W60 (available from BMW with part number 0751009420).

Q: What is the recommended service interval for my ZF S6-40 Corvette transmission?
A: The lubricant should be changed every 30,000 miles.

From the zfdoc.com website info I would change it at 10,000

**Hib Halverson** · 12-14-04, 12:48 AM

I use Red Line Light Shockproof gear lubricant in both my ZFs. Admittedly, RLLS is a very robust formula intended mainly for racing or very severe duty. Probably the best choice for a street/track car is Red Line MTL. Either of these can be run 3yrs or 36,000 miles.

Castrol 10W60 engine oil is, also, acceptable but, according to spectrographic analysis testing I've seen, it needs to be changed frequently. The GM lubricant is ok, too but certainly not a good high-performance choice.