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993 C2 manual gearbox oil type

Found this on RL from a chap complaining about difficulty shifting from 2-3 after trans oil change......may be of interest


I had this problem with my 1997 993 after a transmission oil change. I discovered that Porsche had issued a Service Bulletin stating that only a specific transmission oil type was now approved -- my mechanic had not read the Bulletin and was using some other unapproved product. We drained the new fluid and replaced it with Porsche approved transmission fluid and the problem was solved.

Pelican Parts sells the correct Porsche transmission fluid--this is where I purchased mine. Details below:

Manual Transmission Fluid - SAE 75W-90, (20 Liter)
Part #: 000-043-305-48-OEM
Part #: 000-043-204-19-OEM (Superseded)

Attached here too is the Porsche Service Bulletin.
 
dont buy 20l though! you only need 4 litres or so. (and a proper pump as i discovered!) :thumb:
 
OK, so I changed the gearbox oil this week: a local specialist put in 3.6 litres of Red Line 75W90 NS. The stuff that came out looked in excellent condition (consistent with a recent change by the specialist I bought the car from).

There has been absolutely no improvement in the gear change, so it's obviously not the gearbox oil type or quantity.

Reading around, I'm beginning to suspect that the clutch may need bleeding. It can't be the slave or master cylinder as they were replaced by the specialist before delivery. I understand that there is no adjustment possible on the 993 hydraulic clutch, and that air bubbles may cause problems.

Back to the specialist... (well they did say this would be a hobby, not a car).

:frustrated:
 
I'd still replace the rear engine mounts with either the C4 mounts (slightly less compliant than the expensive C2 mounts) which has helped on a lot of people's cars or go for the RS or Wevo mounts. Plenty of good results with 1st to 2nd improvement and a cheap DIY job
 
RobIpswichUK said:
I'd still replace the rear engine mounts with either the C4 mounts (slightly less compliant than the expensive C2 mounts) which has helped on a lot of people's cars or go for the RS or Wevo mounts. Plenty of good results with 1st to 2nd improvement and a cheap DIY job

Swapped the rear engine mounts yesterday for the RS units (genuine Porsche items). I eagerly got into the car hoping to experience some great improvement in gearshift quality. Big disappointment. It might be slightly better - although I think that is more me hoping that it's better than a real result. The gearshift is still 'crunchy', especially 1st to 2nd and less so in other gears.

So I've now changed the gearbox oil and replaced the engine mounts. What else can I do to fix this gearshift problem? I bought this 993 thinking it was going to be the holy grail of driving experiences, but so far I've had more fun aged 19 in an XR2... :nooo:
 
This really does sound like a clutch problem. If it were the gearbox it seems unlikely that selection of all gears would be affected?
Where is the biting point? Does it seem to be right at the bottom of the pedal travel?
Have you taken the advice already offered i.e. bleed the clutch? With the car on a lift and the undertray removed it takes one spanner, a cupful of fluid and 5 minutes to do. It is however very easy to let the reservoir level drop too low and introduce air if not familiar with the design where the brake and clutch reservoirs are integrated into one. Perhaps this is what happened when the clutch slave and master were changed as you mentioned earlier?

If that doesn't work then I'd be wanting to investigate the clutch actuating fork, clutch cover, release bearing etc for damage or wear.
 
kerb scraper said:
This really does sound like a clutch problem. If it were the gearbox it seems unlikely that selection of all gears would be affected?
Where is the biting point? Does it seem to be right at the bottom of the pedal travel?
Have you taken the advice already offered i.e. bleed the clutch? With the car on a lift and the undertray removed it takes one spanner, a cupful of fluid and 5 minutes to do. It is however very easy to let the reservoir level drop too low and introduce air if not familiar with the design where the brake and clutch reservoirs are integrated into one. Perhaps this is what happened when the clutch slave and master were changed as you mentioned earlier?

If that doesn't work then I'd be wanting to investigate the clutch actuating fork, clutch cover, release bearing etc for damage or wear.

Thanks for the input, KS. The clutch feels good (although this is my first 911 so I don't have anything to compare it to) and the range of movement would seem to be normal. There is no dragging as far as I can tell; if I depress the clutch at standstill and engage 1st there is no sign of creeping forward. This doesn't surprise me as the clutch and flywheel are brand new, replaced by the dealer before delivery less than 3,000km ago.

However, it hasn't been bled by me - perhaps the next step in this saga...

I have already checked the fluid reservoir and it is good. No signs of leaking and it certainly hasn't needed topping up since I collected the car.

Thanks again :thumb:
 
cryddaboy66 said:
I've read on a US forum that many 993 owners there swear by Red Line 75W90 NS (apparently the NS stands for 'Non-Slip') and that it is the ideally suited to the 993 manual box and will resolve my problem. I'm thinking of buying some to try it out.

Can anyone make any recommendations? Anyone tried the Red Line oil?
When I first bought my 993 C4, 14 years ago, the gear changes appeared OK - a few weeks later I changed the gearbox oil and then started to experience 1st> 2nd gear crunch and or bulking.

In an effort to sort this, I went to a local specialist and we then put in Mobil 1 oil with no perceptible change to the gear change quality.

Over the next 13 years The 1st > 2nd change would crunch when cold and all the gear changes were a little woolly to select especially when cold.

When hot (track day hot) the change was significantly improved but during normal driving I could not be confident that I could go from 1st to 2nd and back without a crunch or "bulking" unless I "double de clutched".

As the years went by, the change improved but it was hardly the proverbial "hot knife through butter" that I recall from my four speed Ford gearbox days.

It felt to me that the synchro hub was not "griping" the gear to synchronise the speed as there was too much lubrication between the parts.

Roll forward 14 years, 70k miles and frequent clutch cylinder bleeds and I was still running on the same Mobil 1 as I was reluctant to replace it and mess up the marginally improved gear shift.

A combination of a post on here, where someone found some broken diff parts on the magnetic drain plug and a Land Rover gearbox in my garage with the bits of broken gear on the drain plug meant the engineer in me had to drain the oil, inspected it and change it on the 993.

Four bottles of RED LINE Synthetic Gear Oil 75W-90NS GL5 (non Limited Slip) were purchased from Opie Oils and pumped into the gearbox.

The improvement to the gear change since changing the oil is quite marked, especially 1st >2nd>1st. No need for a "double de clutch" - It worked for me!

I am also pleased to report that there was no bits metal on the drain plug even though I had significantly extended the gearbox oil change interval.
 

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