Race Engine Forum UK

Hi,

I am seeking advice on the correct gearbox oil for a 5 speed Fiat 131 gearbox.

I have two copies of the Haynes Mirafiori manual (manual number 310) one published in 1988 which specifies SAE80W/90, and one published in 1989 which specifies SAE15W/40 multigrade engine oil.

Normally I would go with the latest published data, i.e. SAE15W/40, however the oil drained out of the gearbox certainly smells more like SAE80 gear oil, so I am now in a bit of a dilemma.

Any advice would be gratefully received.

Hi John
This old chestnut has a long history.

On my 124 , much the same as the 131 gearbox, I use a good quality 20/50 (GTX etc.) oil.

Hope that helps?

The oil listed in the factory Fiat manual for that car for road use* is 1.8L of Fiat Tutela ZC90, a non-EP SAE80W/90 gearbox oil containing (non EP) antiwear additives. Forget any other listings you see.

What you use that is not 'correct' is up to you, but using the wrong one can definitely cause abrasive damage the synchro hubs. And if you fill it with a substitute I certainly would insist on it being a gearbox oil not engine oil and not an EP type which contains additives that will cause the same wear.

A trip to your nearest Fiat dealer, methinks?


GC

* I stress for road use because for racing I would use Selenia race gear oil.

Like Guy said, steer away from oils with EP specifications.

EP oils have a good amount of phosphor/sulphur additives which will turn the synchonizer baulk rings into something that resembles molten cheese in no time.

I've been using BP EnerGear 80W-90 in my Lada Niva 5-sp box for about eight years without any problems. Lada boxes are derived fron 124/131 4-speeds so it might work as good for you.

To all,

Thanks for the prompt replies. I'll go with the SAE80W/90 as I'm pretty sure that is what came out.

John

This is the same situation with the ZF Box in the Strada Abarth.