Hello to everybody and happy new year! I have owned my 308QV for 6 months now, done several things, including interior restauration, injection setup with new injectors, york to sanden mod, new suspension bushings, so no many bits left. Of course major manteinande was done before I purchased it, including belts. Next movement will be to change the GB oil. I know it was changed 6 years ago. So, what should I put inside? what are you guys using? Thanks in advance.
SWEPCO 201 80W90 Gear Oil, the blue stuff. That's what my '86 328 has always had in it and I've continued to use it. I'm sure others will chime in with a preference for Red Line Synthetic. I do like the fact that some insist that Red Line eases shifting into second gear? Although, as soon as my car warms up, shifting become very easy.
Any gear oil that meets the specs in the owners manual is fine. Don't make yourself crazy worrying about it.
Redline seems to be the reference, also in other forums of another cars. I've just had a look, but it does not say if it is synthetic. But I assume it will be. The oil you put in your GB is not trivial. It can make a big difference, as tested with my other cars.. I'll try to find redline in europe. Thanks. I'll keep one eye in swepco also...
This was the reply I received from Redline when enquiring about there gearbox oils..... In the Ferrari transaxle the 75W90NS is recommended, the MTL is a lower viscosity than specified and a GL-4 rather than a GL-5. The MTL contains a very slight amount of friction modifier, it is basically a non slippery fluid. The Ferrari limited slip transaxle doesnt typically require a friction modifier, as it doesnt chatter when making a slow/tight turn. So contrary to what you have read or been told, Red Line 75W-90NS would be the recommended fluid. I trust this helps? Simon Roper Sales & Business Manager
I'll be changing the gearbox oil in my 308 QV soon, and after a lot of reading here, I found some consensus on a Redline solution - 3 litres of 75W90NS, and 1 litre of 75W90. Several people here reported that using 4 litres of 75W90NS actually did cause a bit of limited slip diff chatter when making tight turns at low speed, and that the 3/1 mix eliminates that diff chatter.
Note that Red Line has a Friction Modifier additive specifically for use in conjunction with their gear oils such as 75W90NS. Red Line Synthetic Oil - Gear Oil for Differentials - Limited Slip Friction Modifier (I went with straight 75W90NS and am not noticing any problems.)
We used the Swepco for many years and gave up on it because more modern lubricants give far better shifting performance. We have client 308's that have been running MTL for over 100,000 miles and still working perfectly. I use nothing else in my own 328 and have never seen an oil work as well in the 308/328 gear box. If track use is intended MT90 would be an excellent choice too.
In my recently purchased qv I used Mobil 1 because it was readily available. After only 500 miles I swapped it out with redline and the car was happier. The gearbox shifted better overall and cold second gear is nearly gone. Note: I'm in south Florida so cold is relative.
Bingo. That's the combination I have used in a 1984 Mondial QV, '78 308 GTS and my current '86 328 GTS. One quart/litre of Red Line 75W90, and the rest 75W90NS. The one litre of 75W90 puts in enough limited slip modifier so that you don't get "graunching" from the differential in tight turns, but no so much that it interferes with the sychros in the transmission. Because the gear oil does double duty -- transmission and differential -- I've found that this compromise seems to keep both of them happy. And it does help to ease the 2nd gear cold shift problem as well. I know others have used other brands, but I've had good luck in these transmissions with Red Line products. NAYYY, YMMV, etc., just a happy customer.
Good to know. Out of curiousity, does the 308/328 have brass syncros? One of the distinctions Red Line makes between MTL and 75W90NS is regarding sulphur content and MTL being brass syncro friendly. Conversely, Red Line lists Ferrari as one marques where they recommend 75W90NS Gear Oil.
Interesting and confusing.. I noticed this morning, car cold and cold weather, some strange reactions from the transmission in tight turns.. Ok, I think I will try the combination said above 3litres75W90NS/75W/90.. Thanks for your feedbacks. Much appreciated.
Iron syncros Redline goes with factory specs like everyone else. Ferrari says GL5 and so does Redline. GL5 specification is for medium to high offset hypoids. GL4 (MTL) is for low to medium offset hypoids and bevel gears. High sulphur is used as an EP additive. 308/328 isn't hypoid equipped. It does not even have bevel gears like the 348/355.
True. Techy nerd info: From an engineering viewpoint the Hypoid is the animal that requires the special lubrication. The vector forces on helical gears like those in the 308/328, are similar to bevel. The helical design also introduces axial and radial thrust. Though bevel has a much lower power transfer rating, about half compared to spur/pinion where spur/pinion is less then helical. greater gains can be made also if a longer addendum design is used (deeper teeth).
Adding some Redline friction modifier will achieve the same result if you have already put in the NS oil.
