sweet928

So redline, royal purple, some GM retro stuff. Someone tell me which is best please.

Fsharp9

Redline 75w 90ns works great, OB syncros SUCK even at 50k miles I get some occasional crunchies on fast 1st to 2nd or when downshifting 5th to 4th and this made it much better. Only 1 month of use so we will see with long term use if it leaks as some have said. I might even give the GM fluid a try next season but it seems a little thin for a transaxle.

jheis

Agree, Redline.

Tried Mobil 1, no help. Devek recommended Swepco - ackk, pittue - the tranny was almost impossible to shift without painful noises. Drained the Swepco and tried Redline. Ahhhh, much better.

James

linderpat

subscribed

sweet928

That's it? No more feedback?

medipedicman

I have used Redline for my last two 5 sp 928. It really transformed the performance of the 83 but has had a much smaller effect on the 79. I bought two gallons of Swepco from Pelican as an alternative but during this process I have discovered other trans issues that need to be dealt with. I am doing a trans swap (eventually) and will use the Swepco at that time just to try it out.

steve322s

Valivoline VR1, this after Red line and she never shifted better.

jwillman

There was a previous post where GregBBRD in CA who is likely the most knowledgable gearbox guy in the 928 community provided his opinion.

Per the thread linked below his position is he will not warranty a gearbox if the customer uses Redline. He recommends Mobile1 75-90.

Think thats a pretty strong recommendation!

https://rennlist.com/forums/928-foru...le-oils-3.html

sweet928

Did this apply to 79 5 speed trans? That's a different set up than the s4 trans and gts trans. Just want to be sure MY.

joehelendetroit

Tried the Royal Purple and it made no difference at all. Looking to try Redline next.

Mrmerlin

try the GM stuff and report what happens,
my friend has a RS200 rally car and used it,
and said his trans has never shifted smoother,
this after going through a bunch of different fluids.
He got the tip from a race team mechanic for vintage race cars

GlenL

Search.

sweet928

Searched. Too many opinions. Some dated. Was looking for a up to date consensus.

Green Goblin

Had some leak issues with the Redline 75-90, put in Mobil 1 LS 75/90 and seems to have slowed the flow on the ground and shifts as good as with the Redline.

Andy

rjm65

My 79 was nearly impossible to shift up/down in the lower gears (1st/2nd) when I first purchased it. I refilled it with Redline 75/90ns. After the fluid change, upshift 1st to 2nd could be done with minimal grinding, downshift into 2nd or 1st would still grind.

A little over a year ago I changed the oil to GM Manual Transmission Fluid p/n 88861800. I can now upshift normally 1st to 2nd. If I ease the selector into 2nd or 1st, I can quietly downshift with no grinding noises.

I've put over 10K miles on the car with the GM fluid, I've been very happy with it. If I try to rush the shifts (1st to 2nd, 2nd to 1st) it will still grind, but I can drive the car normally with no funny noises coming from the transmission reminding me it needs to be rebuilt.

By all accounts, my trans was shot, and the GM fluid has been as close to a rebuild in a bottle as I've ever found.

The 78 owner's manual states to use Dexron in the man trans, the 79 manual states Dexron can be used when 75/90 is not available. GM Manual Transmission Fluid p/n 88861800 is the fluid to use in manual transmissions/transfer cases that called for Dexron prior to Dexron VI being released. GM TECH BULLETIN: http://www.archivedsites.com/techlink/2007/05/

Raymond
1979 928