garrett376

Hi Guys - I am curious if anyone else out there has found the same result. I recently changed the manual tranny oil in my race car from 75w-90 Valvoline non-syntetic type gear oil (the $2 kind in the white squirt bottles) to 75w-90 Mobil1 fully synthetic gear oil. I decided paying a lot more was worth the theoretical protection under racing conditions.

Well, I was surprised that before the change (with the dino oil) the tranny shifted SOOOO smooth - it would really nicely slide into gear whether it was hot or cold. Now, with the new (and expensive) synthetic oil, it is very notchy at all temperatures - same when hot or cold.

Anyone find this occuring when going to synthetic??? If it didn't cost so much, I'd drain it out and fill it back up with the dino oil!!!

bgiere

M1 from Autozone? That's gear oil, not really the best for synchros...use Mobilube...

here's the stuff:

http://www.lufteknic.com/Merchant2/m...ode=lubricants

There is a very recent thread in the 996 forums on this subject.

bgiere

https://rennlist.com/forums/996-forum/287403-porsche-gear-lube.html

garrett376

Thanks Brant - interesting that there are two types; and it sucks that I bought what I thought was the good stuff! I am surprised that the cheap non-synthetic would be better than even the wrong type of Mobil1, considering the non-synthetic is also gear oil vs. transaxle oil. Shoot!

PS - yes I got it from Kragen Auto Parts

Larry Herman

Yep, Brant has got the right stuff. Bought 12 gallons of it this season.

springer3

Garrett:

I had the same experience 3 years ago when I changed the factory fill with Red Line synthetic. Shift action went from buttery to to point that I double-clutched every shift. I drained the stuff and refilled with M1 75W-90. It got much better, but never got as good as it was. I placed an order for Mobilube, and will give that a try when I do the major service this Fall.

OUR9II

Yikes! Me too. I have no notchiness after the fill (a year ago), but a refill is in order. Thanks to all... lufteknic bookmarked!

Maybe I don't know what I've been missing...

garrett376

So, do you think that I will be wearing out my gearbox at a greater rate with this "better" oil?

Chad T

The way I understand these gearbox lubes is that they have modifiers that actually help the synchros grab which makes the car shift easier. Don't know if them not grabbing would cause more or less wear or just harder shifting. I've used Synchromesh transaxle lube before as well but don't know if it is suitable for a 964. Does anyone know if the Mobilube is good for LSD?

JasonAndreas

I had the same issues with store bought Mobil-1 (on right) but things got better once the gearbox warmed up. Hopefully I will fill up with SHC (on left) before Thursday and report back.

Heirsh

I put swepco in mine and noticed no improvement. I have some issues when the car sits for a while (more than a week). If its driven regularly its pretty good. Still, I was hoping for a bit of an improvement in my shifting that i did not get witht he Swepco. Its not worse, but its not better either.

I'm eagerly awaiting your results Jason.

bgiere

Mobilube has everything needed for LSD, no need to add friction modifier in most cases. If you experience chatter add an ounce of your favorite LSD friction modifier and try again...keep adding until the chatter subsides.

KirkF

With my 944 I made the mistake of putting synthetic in. The gear noise from the tranny was unbearable and I ended up dumping it all out and replacing it with regular dino gear oil.

I put LiquiMoly synthetic in my 964, but I've had no problems with it.

Kirk

garrett376

So with increased noise, and poorer shifting, it seems that this stuff will wear things out more, no????

dougn

i change out with redline synthetic with much improved shifting cold and hot. i was told the shifting is sensitive to oil because of the friction or lack of friction spinning the syncros. the right oil will sync the gears better. that said...i'm not sure what redline i put in there but it definately works well.