That you may want the GL-5 gear oil. 928s spec GL-5 and that's a GL-4 oil.

What's that mean? Heck if I know but I've run the GL-5 gear oil for almost ten years and it works and stays in the tranny.

http://www.redlineoil.com/product.aspx?pid=47&pcid=7

Mix in the plain 75W90 if you've got a limited-slip differential. Search for more on NS vs plain.

 

have you tried bleeding the clutch line? Also could be a master/slave piston not sealing well in the cold

 

Still need the information as to when the problem first appeared, and exactly what was done to the clutch, but I was originally thinking intermediate plate adjustment or lack of stub shaft lubrication (as Glen has also suggested) ... or a number of other clutch issues like stepped wear in the stub shaft splines, exacerbated by lack of lubrication.

I've had those exact symptoms on my 82 5 speed and they were temperature dependent ... cold = grinding, normal temp/hot = OK but still grind into reverse, really hot after a thrashing = grinding into reverse and sometimes great difficulty getting into gear when moving. All fixed with correct clutch setup and adjustment.

You need to know what was done, and importantly what wasn't done, to the complete clutch assembly. I think you need to get the clutch spot on before you can assess whether you have a trans or oil issue ... and there's a good chance it's not right now.

 

I have not experienced any leaking with Redline. I think having a synthetic in the engine you might find a leak or two (in the engine) or so I've heard.

 

Thanks, GlenL

 

being it is an OB 5 speed, are you aware the early 5 speed 2nd gear sycro's are weak. My 79 did this. They say Royal Purple gear oil will fix it. Being mine only did this in 2nd gear, I drove the car shifting 1-3-5 when I was not "getting on it" I actually found the car a lot easier to drive like this around town. A lot less shifting and the car had plenty of torque to skip 2nd gear. As soon as the transmission heated up it was fine. You may just have the 2nd gear syncro issue.

 

I'm not saying it will leak...but I will not warranty a rebuilt transmission against leaks, if someone uses this fluid. Leaks out the seals almost as fast as you can pour it in, when I've tried it.

Mobil 1 "LS" 75/90. Auto Zone has it on their shelf. You, nor anyone here, will never "need" more transmission fluid than this. Never.

If it grinds with that, you need to go back and fix the clutch.

 

Make sure you order it (for store pick up) on Auto Zone's site as it is about half the price (10.99 vs. 20.99). At least last week was so.

 

When I was racing the Alfa, I had 2nd gear syncro issue and in a racing environment it can get dicy when you really need a second gear in a hurry. I was using SWEPCO and I was advised by one of the Alfa guys to use factory spec Shell 90# gear lube.
I did and 2nd gear worked perfect after that. Some also said that Porsche boxes and Alfa boxes were engineered by the same company. Not sure if this is true but it was always good for a laugh.
Moral is: Gear oil is a big deal! Greg Brown is right

 

The fluid was changed when they did the clutch. Since then, I have put about 250 miles on it. Each day it has improved a little... First couple days were 10-15 minute warm up, then 5-6. Today it was 90 seconds for reverse to work, & I could get it in 3rd & 4th (parked, obviously) immediately after starting. Thats kinda ok. Maybe with all the parts changed, and the new oil, it is fixed and just needs to be driven?

I'm pretty sure this car was barely driven, if at all, for at least the past year before I got it.

 

FWIR, The GL-5 lubricants are designed to cope with the sliding action of hypoid gear interfaces. Quite often, but not always [dependent on the chemistry], GL-5 type lubricants are not compatible with synchromesh transmissions.

Redline has one, but most 75W-90 GL-5 gear oils have viscosity and frictional properties that are designed for differentials and not synchronizers. Redline also makes a GL-4 called MT-90 and it also works well in manual gearboxes that call for 75W-90 viscosity gear oil.

I will go with Mobil 1 LS 75/90 as Greg advises, no replacement for experience.

 

Porsche Techincal Bulletin #8813:

"Transmission oil labeled API service classification GL 5 or MIL-L 2105B must be used on all Porsche models. Oil classifications such as GL 6 and GL 7 may cause syncronizer failure and are not recommended."

I ran GL 5 classification gear oil in all the cars I worked on, for the 24 hours of Daytona, where syncro performance is the #1 priority. I run this classification gear oil, to this day.

I ran GL 6 classification gear oil in the cars I worked on, for the 12 hours of Sebring, where getting a ring a pinion to "live" for 12 hours is very difficult. Yes, the syncros "crunched" the entire race....but had to be sacrificed to have a ring and pinion, at the end. I never found a gear oil that would do both.

 

Greg, thanks for that last post. Great information.

 

Yes Greg, Thank you.

But what are your thoughts on adding a little Synthetic Redline MTL to the majority of the Mobil 1 LS?

Could it improve people's hard shifts granted their clutch is adjusted correctly?

Most of us are not doing 12 hours at Sebring with our early cars,

1/2 hour cruising at low speeds..

 

That gear lube is rated GL-5 which is what Porsche recommends. Perhaps you missed that. Are we all agreeing?