Join Date: Dec 2006
Location: huntsville, alabama
There shouldn't be any difference in a duetto or later 105 tranny. Well there are a few difference between a 1600/1750 and 2liter gearbox, but nothing is different concerning which oil to use. I've had a better gearbox after putting in redline but like Tom says there are a few outliers but I've heard nothing catastrophic from the outliers. When its cold there will definitely be a difference in the stiffness of the gearbox--the synthetic oil doesn't need to be warm to be thin and circulate and not be syrup. My understanding is the NS does not have the slippery additive (friction modifier) in it. Our transmissions don't need it or want it because of the type of alloy used for the synchronizers--they need friction to work properly. Like you, I used the the non-NS in my stock (non LSD) rearend . I don't think it would have mattered if I had used the NS in the rearend--but it does matter in the tranny. Our rearends have no clutches which are the "maybe" issue with NS vs non NS in the rearend. Richard says, and I'm sure he'll reprimand my post if I'm wrong, that the LSD clutches do need the NS and it makes sense to me that you want the clutches to catch in a LSD. Others say you need the non-NS in the rearend.
I did change out the tranny fluid in my 99 toyota tacoma 4 wheel drive manual 5 speed from toyota gearoil to redline ns. They have the same type or similar alloy alfa uses in the synchros. No grinding or crunching before or after the change but the shifting is smoother and on a cold morning the tranny shifts like its at full temp and been there a while.
There are many post on the BB with lots and lots of discussion (kind of like which engine oil should I use) and redline NS appears to be the best choice for the 105 trannys. Run it for a while and let the new oil replace the old oil on all the parts and see if it gets better. I've read suggestions to clean out the old oil with kerosene for a few mile before making the change but I haven't done that on an alfa (but I have done that on a really old chevy tranny years ago to flush out the rust from the dry gears)
Frank Livesay Huntsville, AL
Green Alfa - 68 Canadian 1750 Spider Veloce (driver)
White Alfa - 68 Euro 1750 GTV (needs a refresh)