bgiere

The bottom line is that some trannies may have synchros which require a less slippery formula to get them to perform correctly. In those instances i have had success with Valvoline Durablend (semi-synthetic). Other boxes will do fine with a very slippery transaxle fluid (such as Redline)..so far in my case the best engagement and LSD operation was acheived with Mobilube SHC. I have also sent the fluid in for a UOA (used oil analysis) after 25 racing hours and it came back with a stellar report. I had used Redline in the past and it was pretty darn good, but the Mobilube takes the prize for my car.

Cupcar

I have a 911 GT3 Cup factory guide and it calls for Mobilube SHC for the gearbox, funny it is not easily available in the USA and that the normal Mobil Synthetic is not up to the job.

AOW162435

I drained my factory oil last month and filled the box with Mobilube SHC. I can honestly say that shifts are now smoother than before. I really had no issues with the original oil, I simply wanted to drain the 12-year-old, 41,000 mile oil. After all of the horror stories on the 993 board regarding the various oil options and less-than-stellar results, I'm glad I found the SHC.

Andreas

Colin 90 C2

How many quarts are needed for an oil change?

AOW162435

Just under 4 quarts. I filled the transmission and then let any excess drain from the fill hole. The car was perfectly level on four stands.

Andreas

JasonAndreas

The one thing I saw mentioned that I still haven't seen an answer to is what effect the material used to make the syncro's has on the lube selection? The G50/G64 in the 964 and 993 uses Brass syncro rings while the Cup Car gearboxes come with steel.

chancecasey

there are a couple of great thread on this on pelican.

just a random data point - I don't know what used to be in my tranny but i'm 90% sure it was whatever was from the factory. I used the specified swepco dino on a refill and now, when the tranny gets a little warm from high revving, gear selection becomes very notchy and sometimes as if i'm not even pushing the clutch down. let it sit for a few hours and it's smooth again.

Cupcar

Interesting point.

What is strange is that the factory only specifys the Mobilube SHC specifically for the 996 Cup- which had basically a steel syncro G50 gearbox like the 964 RS but with 6 gears.

The only specification given in all the Porsche factory books I have for transmission lubricant is: SAE 75W90 gear oil, API classification GL 5 (or Mil-L 2105 B). No other spec given for use in the RS which has steel syncromesh.

The Mobil 1 synthetic gear oil available here in USA exactly meets the specification required by Porsche, but apparently does not work as well as their Mobilube SHC.

Bill Verburg

In the 993 Supercup and GT2 tecj info for Rennsport
factory recs are
Monilube SHC
Veedol SAF 44
Castrol SAF-XJ

I'm using Monilube SHC in my /30. Seems to do the job.

craig001

I've run Redline in all my Porsches and had no issues.

JasonAndreas

There is a TSB for the model 996(s) with "Approved Transmission Oils" that lists:

000-043-204-20 Mobil (Mobilube PTX) - 20 Liter container
000-043-204-19 Shell (Transaxle) - 20 Liter container
999-917-546-00 Shell (Transaxle) - 1 Liter container

so I wonder if maybe the PTX might be a better choice than SHC for brass syncros?

Have you done any cold weather driving with it?

Bill Verburg

No, neither of my Carreras is driven in cold weather.

bgiere

For cold weather driving I have used Valvoline Durablend and the shifting action was quite good. I have used the Mobilube SHC in early April at the racetrack (45 dgrees F) and it was fine.

Geoffrey

I'm using up the last of my old Mobil 1 75/90w in my trans which has steel syncros. No issues. The Mobilube SHC has been renamed Delvac SCH. Interesting the Mobil oil I run in the diesel truck is Delvac diesel oil.

B.Kish

Interesting Discussion.

FWIW I used a mix of 75-90 Redline and 75-90NS Redline in my RSA and all seems well. I still get a slight gronk in my 2-3 shifts, but not bad. The LSD seems to hook up OK also.

I did find this online. A Mobilube SHC 75-90 LS

http://www.ibg.ge/lubricant.asp?lubID=15