131mirafiori forum

Getting ready for 3ma09:
OK im going to change the oil in the gearbox, now the old stuff comming out is the sticky grapefruit smelling 80W/90EP, however as we all know the manual says 15W/40.
The car is in Spain and likely to be subject to average tempereatures higher than those in the UK.
So what do i replace the oil with? and why.
Steve

NO! Never use an EP gear oil in a Fiat 131 gearbox. The EP (Extreme Pressure) additives can ruin a Fiat 131 gearbox because they will damage the brass in the bearings of the gearbox. The correct oil to use is Tutella ZC-90 or any GL3 specification gear oil. Do not use GL4 or GL5 specification oils as they are all EP oils.

Now a 90 grade gear oil has the same viscosity as a 30 grade engine oil so if you cannot get the Tutella ZC90 oil (available from most Fiat dealers) then use a straight 30 engine oil (available from most motor factors). In fact you can use multigrade engine oil in the gearbox but I wouldn't go for a modern and thin 5W/40 (or worse 0W/40) but go instead, as you rightly said, for a 15W/40 or a 20W/50.

 

I think mine has Castrol GTX in it at the moment. Not sure if this is right but the box seems to perform OK!

I thought this was only an issue with the 124 gearbox. I'd better go and change my oil, I've got an EP gear oil in it!

what 're yo talkin about? i'm running 80w/90 in my 132 for 10 yrs, same in lada with 131/132 gearbox for 2 yrs now. no problems whatsoever...

80W/90 is fine. It's 80W/90EP that could be a problem (according to Fiat).

Any idea what EP means? must be some sort of syntethic oil?

EP is extreme pressure additives to reduce wear on gear contact faces I believe. Happy to be enlightened further!

From Wikipedia: (http://www.answers.com/topic/ep-additive)

EP additives, or extreme pressure additives, are additives for lubricants with a role to decrease wear of the parts of the gears exposed to very high pressures. They are also added to cutting fluids for machining of metals.

EP additives are usually used in applications such as gearboxes, while AW additives are used with lighter load applications such as hydraulic and automotive engines.

EP gear oils perform well over a range of temperatures, speeds and gear sizes to help prevent damage to the gears during starting and stopping of the engine. Unlike AW additives, EP additives are rarely used in motor oils. The sulfur or chlorine compounds contained in them can react with water and combustion byproducts, forming acids that facilitate corrosion of the engine parts and bearings.[1]

EP additives typically contain organic sulfur, phosphorus or chlorine compounds, including sulfur-phosphorus and sulfur-phosphorus-boron compounds, which chemically react with the metal surface under high pressure conditions. Under such conditions, small irregularities on the sliding surfaces cause localized flashes of high temperature (300-1000 ?C), without significant increase of the average surface temperature. The chemical reaction between the additives and the surface is confined to this area.

The early EP additives were based on lead salts of fatty acids ("lead soaps"), "active sulfur" compounds (eg. thiols and elementary sulfur), and chlorinated compounds. During the 1950s the use of lead soaps was eliminated and replaced by zinc and phosphorus compounds such as Zinc dithiophosphate. [2]

Some of the EP additives are:

    * Dark inactive sulphurized fat
    * Dark active sulphurized fat
    * Dark active sulphur hydrocarbon
    * Short and medium chain chlorinated alkanes (see chlorinated hydrocarbons and chlorinated paraffins)
    * Esters of chlorendic acid
    * Polymer esters
    * Polysulfides
    * Molybdenum compounds

Aliphatic chlorinated hydrocarbons (chlorinated paraffins) are cheap and efficient, however they persist in environment and have strong tendency for bioaccumulation. Therefore they are being replaced with alternatives. In cutting fluids, their role is largely confined to formulations for forming complex stainless steel parts. [1]

The activity of halogenated hydrocarbons increases with decreasing stability of the carbon-halogen bond. At local contact temperatures ranging between 305-330 ?C, the additive thermally decomposes and the reactive halogen atoms form a surface layer of iron halogenides on the part surface. Eventual failure of the contact point comes when the contact temperature exceeds the melting point of the iron halide layer. Under such conditions, small particles of carbon are generated as well. Some compounds used in lubricant additives are chloroalkanes, trichloromethyl phosphine acids, organic esters of a-acetoxy-b,b,b-trichloroethyl phosphonic acid, trichloromethyl esters of phosphoric acid, trichloromethyl derivates of sulfur, trichloroacetoxy compounds, esters or amine salts of chlorendic acid, 1,2,3,4,7,7-hexachloro-5-dimethylbicyclo[2.2.1]-2-heptene, etc.

Oil-soluble organophosphates, with or without zinc, have excellent high-pressure and antiwear properties, and provide corrosion protection especially in presence of chlorinated hydrocarbons. ZDDP starts decomposing at 130-170 ?C, while the activation temperature of TCP typically exceeds 200 ?C. Their reaction products form a chemically bonded lubricating film on the surfaces.

Polysulfides serve as carriers of inactive and active sulfur.

Molybdenum compounds decompose under high pressure to form an in-situ deposited layer of molybdenum disulfide. Molybdenum dithiocarbamates are used as additives for greases.

Sulfur containing EP additives can cause corrosion problems in gears with parts made of bronze, brass and other copper alloys when high temperature environment is encountered.

In my many days in a fiat garage all gearboxs 131s 132s stradas  etc all were filled with a standard 15w40 oil (we used duckhams hypergrade-so much for olio fiat !) as was prescribed by fiat ,made the box a bit sticky in the winter but soon freed off in a few minutes of turning over - any EP oils killed gearboxs -especially in stradas(reverse and second gear-shared the same synchro ring and shredded the brass)
So if anyone has EP in their box be warned -its good advice  ;)

Anyone care to start a new thread on diff oils :) :)
Anyone lost their rear diff  :) ??? Would love to hear from people with series 1 132s and 131s  ;D ;D-series 2 131s as well  ;D

I had been running GL-1 90 in my Yugo and it was very difficult to shift in cold weather (10F to 20F).  After swapping to 20W50, it now shifts as easy when cold as it does when warmed up and the engine doesn't struggle during warmup. I'm glad I did it.

The Yugo owner's manual says to use 40 weight oil but I've never seen it on shelves. Shell Rotella 30 weight is hard enough to find. That's what most older 1 cylinder engines use.

My 124 Spider doesn't like being shifted into 2nd gear when cold at any temperature until it warms up!

forget what manual says, whole ex-yugoslavia was and still is running yugo's with sae90 in the gearbox.

Hey guys, we run a castrol gtx gear oil, 15w 40 in our 124 spider abarth and in my turbo panorama, with a nulon gear additive and it is fantastic, beautiful smooth shift, smooth and quiet even when you first drive off in the morning, ill get details on it tonight when i can, would highly recomend using the nulon additive, i was never a fan of them untill i tried it and im in love with it especially in these older gearboxes, we even run it in our punto grande sport abarth and its prolonged the life of the oil and gear.