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Full SYNTHETIC - at least that made my '91 with 20K on it shift beautifully, compared to some balkiness on both first and second synchros with the original lube in it. Just changed 3 days ago, and I really like the improvement.

Gary Knox
West Chester, PA
 

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Many here, including me, like Redline. Get it from Centerline or IAR. Some of the newer oils have additives that are too slippery for older Alfa gearboxes. At least thats the explanation I have read.

Jeff
 

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Some of the newer oils have additives that are too slippery for older Alfa gearboxes.
the 1950's era synchro design in our Alfas use little centrifugal clutches to speed up or slow down the dogrings. these require friction to function correctly, hence the gear oil must have the right friction properties.

ENG622, what year Duetto do you have ?
pre '69 cars require GL-1 spec gear oil. '69 and newer specify GL-5

many like Redline. many do not - including myself. the shift feel became very notchy and the gearbox leaked like a sieve.

IAP sells whichever you need :
Redline MT-90, which is GL-1 rated
Redline 75W90NS, which is GL-5
Spirax HD gear oil, GL-5, which is factory recommended by Alfa
i am not familiar with what non-synthetic GL-1 to recommend.

also, shift technique makes a huge difference in synchro life and performance. don't rush the upshifts, and double clutch/match revs when downshifting.
 
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