Why EP gear oil not recommend in a transmission?

[TurboFiat124]

FIAT recommends GL-1 90 weight gear oil in the transmission. Somewhat hard to find at autopart stores but can be sourced from places like Tractor Supply because it is used in Ford tractors. Usually in 5 gallon buckets but not very expensive.

http://www.tractorsupply.com/en/store/travellerreg%3B-ford-tractor-all-mineral-90-transmission-fluid-2-gal

I *think* this is GL-1. I've heard GL-1 is a mineral oil and the bottle says mineral oil but nothing about GL-1. What kills me is manufacturers don't always put the full name on their products. This company is calling it SAE 90. So is it the same as GL-1 90?

I've owned these cars for over 20 years and the word on the street is if you use an EP differential oil (e.g GL-5 75W90) it will destroy the brass syncronizers.

I have heard that EP gear oil (the additives) will destroy wet clutches in motorbikes in no time.

So what's in EP that is OK for a ring and pinion differential but not a transmission? Will the additives truely "eat" the brass syncronizers in a manual gearbox?

By the way. Some people like to run 20W50 (for easier wintertime shifting) in their Fiat transmissions however I tried this in my Yugo and 3rd would grind when I shifted from 2nd to 3rd. I went back to GL-1 90 and no more grinding. I fould bits of brass in the oil I drained out of it.

 

[Roadkingnc]

The ep additives eat brass

 

[Kira]

Hello, Pre-apologies for not being a chemist.
I read here that the sulphur compounds which give differential oils (GL-5's-?) their characteristic toughness are the ones which eat brass synchros.
Ergo there are none of those compounds in transmission oils (GL-4's-?).

If there is a list of "GL" specs out there, please post. Kira

 

[chrisri]

Hi TurboFiat124.
You don't want a GL 5 fluid in your manual transmission because of its high anti wear additives that is almost double compared to a GL4 oil. Additives in GL 5 oil are so strong that layer of AW additive on synchros will peel brass actually and not additive itself because its stronger than brass. Anyway don't use GL5 oil in any manual box that doesn't call for it. My transaxle Fiats actually do use GL 5 MTF, but that's a different design.

I had 124 and a 131 Supermirafiori, best fluid for those gearboxes are ANY GL4 with SAE 80w90. GL1, 2 and 3 are obsolete specification and GL4 is direct replacement for them. You can use it with confidence, GL4 will protect your box much better.

Cheers.

 

[KD0AXS]

Yep, GL-4 is what you need. I doubt you can actually buy GL-1 anywhere. This is what I would use

 

[46Harry]

SAE 90 GL-1 gear oil is available at most NAPA stores in gallon jugs. If they don't have it in stock, they can order it for you.

 

[TurboFiat124]

Thanks guys. Yes I have purchased GL-1 90 at NAPA in the past. I can't recall where my current jug of oil came from.

It may have been a tractor parts store. That jug just says "90 weight" but smells like the imfamous GL-1 I've used in the past.

Unless you pump it into the gearbox, it took me about an hour to refill the transmission on my Yugo. I'd fill a 1 liter funnel and go do something else, come back 15 minutes later and refill the funnel.

As far as refilling a gearbox with this stuff in the winter. Forget about it. It pracically turns to a solid below 0C/32F.

 

[Chris142]

I have used sae50 engine oil in transmissions instead of gear oils.my old truck called for sae50 and my new one calls for gl-1 sae90 but both have the same trans.

 

[BigCahuna]

Some motorcycle specific 20/50 wt oils have a GL-1 rating. Amsoil, and Mobil 1 V-Twin oils have it as well as Valvolines MC oil. They are for use in the motor, primary and transmissions, so they should work in your application. I know you said you tried 20/50 and it caused notchy shifting, but these are made for transmission use. Not all 20/50 wts are recommended for transmission use.,,

 

[chrisri]

Just put GL4 80w90 oil in your 124 gearbox. Forget GL1 fluid, it's obsolete, and don't even think about putting engine oil in that transmission!

 

[antiqueshell]

Originally Posted By: chrisri
Just put GL4 80w90 oil in your 124 gearbox. Forget GL1 fluid, it's obsolete, and don't even think about putting engine oil in that transmission!


This. GL-4 will actually prolong the life of your
synchronized transmission.

NEVER USE GL-5 in a unit that originally called for GL-1,2, or 3.

 

[TurboFiat124]

Originally Posted By: chrisri
Just put GL4 80w90 oil in your 124 gearbox. Forget GL1 fluid, it's obsolete, and don't even think about putting engine oil in that transmission!


My Yugo's owner's manual says to use SAE 40. But now that I've been on this website (and learned a whole lot about oils), I'm not sure if it is referring to engine oil or gear oil since there would be a big difference in "40" between the two. I'm assuming it means gear oil.

Maybe I haven't looked hard enough but I've never seen SAE 40 gear oil.

Even though the Yugo gearbox is made off Fiat tooling, I've been using GL-1 90 weight what Fiat calls for. But shifting is very hard in winter. I may give this GL-4 80W90 a try. I'd like to improve it's shifting.

 

[TurboFiat124]

Still wondering about what "EP" means as far as components are concerned. A differential is not under pressure because it's usually vented to the atmosphere.

I'm assuming when they refer to as "extream pressure" it's referring to the pinion and ring gears making contant with one another?

Where as in a transmission, there are gaps between the gears with low pressure?

Or am I totally off base?

 

[chrisri]

Originally Posted By: TurboFiat124
Still wondering about what "EP" means as far as components are concerned. A differential is not under pressure because it's usually vented to the atmosphere.

I'm assuming when they refer to as "extream pressure" it's referring to the pinion and ring gears making contant with one another?

Where as in a transmission, there are gaps between the gears with low pressure?

Or am I totally off base?


I thought you asked question about 124 gearbox. In Yugos prepared for historic racing people use 80w90 GL4 fluid. It works well.
In your earlier post you said that you got issues with handling of Yugo. There are some modifications to overcome this.
Try to find a 128 shocks and springs, both are stronger and springs are shorter for about 3 centimetres. Front wishbones from a Regata are worth swapping too since bushings are bigger. You should also consider this to improve stiffness of your engine bay since weak bay is known issue in Yugo. Link below;
http://www.njuskalo.hr/tuning-lezanje/donje-pojacanje-prednjeg-kosa-yugo-zastava-101-oglas-2399848

 

[MolaKule]

Originally Posted By: TurboFiat124
Still wondering about what "EP" means as far as components are concerned. A differential is not under pressure because it's usually vented to the atmosphere.

I'm assuming when they refer to as "extream pressure" it's referring to the pinion and ring gears making contant with one another?

Where as in a transmission, there are gaps between the gears with low pressure?



Or am I totally off base?


EP refers to Extreme Pressure additives. The main chemistry is a strong dose of Sulfur-Phosphorus compounds added to base oils.

The pressure being discussed is the loading or contact pressure at the surfaces of the offset drive pinion with respect to the ring gear, and the torque seen in the differential spider gears. A fluid with a protection rating of GL-5 is specified for the above.

Generally speaking, the higher the torque the greater the contact pressure.

In most manual transmissions, you have helical-cut spur gears that are less loaded than are differential gears and what is needed are high levels of Anti-Wear additives with a fluid with a protection rating of GL-4, additional friction modification additives for the synchronizers, and the right viscosity.

 

[TurboFiat124]

Originally Posted By: chrisri



I thought you asked question about 124 gearbox. In Yugos prepared for historic racing people use 80w90 GL4 fluid. It works well.
In your earlier post you said that you got issues with handling of Yugo. There are some modifications to overcome this.
Try to find a 128 shocks and springs, both are stronger and springs are shorter for about 3 centimetres. Front wishbones from a Regata are worth swapping too since bushings are bigger. You should also consider this to improve stiffness of your engine bay since weak bay is known issue in Yugo. Link below;
http://www.njuskalo.hr/tuning-lezanje/donje-pojacanje-prednjeg-kosa-yugo-zastava-101-oglas-2399848 [/quote]

I know for a fact that Fiat 124 gearboxes called for GL-1 90 but was not 100% sure about Yugo gearboxes. I know my Yugo seems to prefer GL-1 over 20W50 engine oil. Most likely because it has well over 100,000 miles on it. As far as I know.

My original post concerned EP gear oil and brass synchronizes. I was just wondering what "extreme pressure" means in terms of the ring and pinion differentials.

I already have those "skis" or stabilizers on my Yugo. I also built a strut tower brace out of wheel spacers and pipe and attached an upper brace from a Fiat X 1/9 which acts as a four engine mount. Otherwise the gear shiftier rocks violently between shifts.