128 transmission oil

I agree with the above. If you use redline...

Make sure to use the heaver MT90 as the lighter weight MTL will seep out the boots on a four speed.
 
The viscosity of NAPA GL-1 is very close to the same as Redline MT-85 (at 100 degrees celsius). I've never used MT-85 in a Fiat transmission and I haven't heard of anyone else using it either so I can't say how well it works. GL-1 is outrageously thick at room temperature which is one of the reasons why so many people don't like it.
 
I've been happily running MT-90 for years. A new gasket set and new boots meant no leaks for years, even with the synthetic.
 
Went to Napa today per Jeffs suggestion and price noted.Employee said they only had GL2 and GL3 and said that they substituted and were the same as GL1.Told him what I saw on their website and produced the part number.He looked into the sky/ceiling with priceless face!! .....lol.Lady employee next to him immediately pulled it up in their computer and said they didn't have any at the store........she looked at him and he took over the sale again and promised to have them at their store in the afternoon.Told them ill be there tomorrow morning.Asked him why he was misleading me into buying something that I wasn't exactly looking for......he apologized saying he thought GL1 was phased out of the market.

Price $12.99 gal plus tax......im happy.Thanks Jeff!!
 
The GL1, 2 and 3 specification was phased out almost twenty years ago. It's a good bet that GL1 is little more than a marketing name these days.
 
Perhaps, but...

It was my understanding that only the GL-2, GL-3 & GL-6 API designations were deemed "inactive" as of mid-1995.

http://www.oilspecifications.org/api_gos.php


The only API Gear Oil Service Designations listing I can find online is from July, 1995, where it lists GL1 as still (at that time?) being a current-use Service Designation:

http://www.api.org/certifications/engineoil/pubs/upload/1560.pdf

3.1 API GL-1
The designation API GL-1 denotes lubricants intended for manual transmissions operating under such mild conditions that straight petroleum or refined petroleum oil may be used satisfactorily. Oxidation and rust inhibitors, defoamers, and pour depressants may be added to improve the characteristics of these lubricants. Friction modifiers and extreme pressure additives shall not be used.

API GL-1 lubricants are generally not satisfactory for many passenger car manual transmissions. However, these lubricants have been used in some truck and tractor manual transmissions. Lubricants meeting service designation API MT-1 are an upgrade in performance over lubricants meeting API GL-1 and are preferred by major commercial vehicle manual transmission manufacturers. In all cases the transmission manufacturer's lubricant quality recommendations
should be followed.

The original Fiat 128 trans gear oil was Fiat ZC90, basically an SAE 90 non-EP gear oil, which is where GL-1 suffices. The Redline MT-90 is a more modern step up from GL-1, but pricey. Most GL-5 oils I've found today are EP-rated for hypoid type gears, which is contrary to what the OEM 128 spec calls for.

While looking up the trans gear oil spec in my old 128 Specs Manual just now, I came across a hand-written note scribbled on the page margin by the previous (original) owner of my 128, calling out the specific use of either GL-1 or Mobil Lube C-90. I've never heard of/seen this Mobil lube before, but apparently it's out there:

http://www.mobil.com/Argentina-English/Lubes/PDS/GLXXENCVLMOMobilubeC90_140.aspx

Now where do we find this stuff? :hmm:
 
Matthew said:
The viscosity of NAPA GL-1 is very close to the same as Redline MT-85 (at 100 degrees celsius). I've never used MT-85 in a Fiat transmission and I haven't heard of anyone else using it either so I can't say how well it works. GL-1 is outrageously thick at room temperature which is one of the reasons why so many people don't like it.
Click to expand...

I remember the first time I was refilling my old 128's transmission in HS and being utterly AMAZED at how resistant the 'fluid' was at coming out of the bottle, no matter how hard I squeezed the bottle!!! :)
 
The viscosity of NAPA GL1 is 13.5 cSt at 100 degrees celsius. Redline MTL is 10.5, MT90 is 15.6 and MT85 is 12.0. However, at 40 degrees Celsius the Redline oils range from 54.1 to 90 cSt and NAPA GL1 is 234.9 cSt at 40 degrees. This is good and bad. Bad in that in makes for poor shifting when cold but good because, in a four speed, the cold oil collects in the boots, never really warms up and stays so thick it helps prevent leaks.
 
Apologies for the thread hijack question but how much transmission oil is needed for the 128 box?

Cheers
Jamie.

ps I'm away with work and away from my manuals!
 
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