355 Amsoil... API GL-4 or Gl-5 Oil For Gearbox Oil?

I had terrible luck with thier gb oil. I mean it turned my car driving into a chore I did not enjoy. Shell spirax made the gb feel like a new car, can even shift into second when cold. Real pleasure to drive

Still use Amsoil in the engine however.

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GL5 is really a hypoid differential oil and GL4 is really a transmission oil. Ferrari specifies GL5 even though the 355/348 transaxles do not have a hypoid differential. Many people have used GL4 oils in those for years including track cars and Challenge cars for many miles with no ill effects.


GL5 oils are made with additives that make the oil particularly slippery for the high shear encountered in hypoid gears. That slipperyness inhibits the function of syncros in many transmissions.

 

I tried the Severe Gear Oil yes. To Brian's point many have better luck with GL4. That was my next step if the Spirax did not work well, works great for me, other cars may experience it different. That's true with most oils so it seems.

 

Get ravenol vsg and be done

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@Rifledriver Is there any particular GL-4 you like/recommend?

 

I usually use Redline MT90.

 

It is still a GL5.

 

Agreed .. but it seems like it is a perfect match for our cars .. it works great in the 360 and the 430 so I figured it would work great in the 355 ?

 

I do wonder why it’s a perfect match for any of those? It’s still a GL5 and only touts “good compatibility with non ferrous materials” - no idea what “good” is?

API GL4/5 standards say nothing about yellow metal compatibility. We just assume GL5 is not ideal because of the EP additives usually used don’t play nice with the brass synchros.

 

Based how it is recommended / has approvals from a ton of manufacturers that have similar design (gear box and diff in one..including some high end cars) plus it does suggest that it is not going to hurt your soft metals. I always like to get what the manufacturer intended (spirax) and this comes the closest and easier to get. Besides working with some Ferrari owners that have used it and they all like the way it performs ..no chatter ..smooth shifting etc.


Only time will tell with regular oil analysis to see if any thing happens.

I understand why someone would choose a gl4 but based on how it is performing in some 430 and 360 so far this is what I choose

Now if you were to tell me you were comparing gl4 to Mobil 1 sync gear oil ..then i would definitely use the gl4 in the "soft metal" gear boxes

I used Mobil 1 sync gear oil in a 512tr with better results than shell approved "Ferrari oil" ..tf1055



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I have used in in a couple of cars and found it good but unremarkable. However the lubrication needs of 360 and 430 are very different from 355.

 

I guess you have not been reading. And we know GL5 is hard on the brass syncros. I have yet another 360 here with all of the syncros trashed without a great many miles. Problem is their differential gears need GL5. It isn't a new subject to me. I have been studying it for a number of years.

 

Thanks for the insight ..can you give me a few differences .. I always like knowledge TIA

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Reread post 3.

 

Ok ..got it ..the diff on the 360 is different than the 355 and for that matter the 512tr

Thank you

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I dont quite understand your comment as I’m agreeing with you and the danger of gl5+brass.

Anyways, Can you post photos of these synchros? Really interested to see what it’s doing to it.


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Brian,
Hope you've been well.

I've been following this for years and appreciate the feedback you've given.
With the research and observation you've done over the years what do you think is the solution at this point in time for the 360 ?

Thanks,

Skipp

 

I wish oil companies would be a little more honest in their advertising. I know GL5s have many different chemical make ups and Ferrari with their rather undersize and highly stressed hypoid diffs need it yet some are attacking brass. I do not believe all are but we just do not know. Rating any GL5 as GL4 and 5 is just BS. It completely ignores a very important attribute of the GL4 spec. I have a great big box of 360, 550 etc syncros that are destroyed and the damage is picture perfect for the failure attributed to GL5 damage. Very few cars have transaxles with brass syncros and hypoid diffs so no one really cares. In the old iron syncro cars it inhibited good shifting but rarely caused damage. As is there really isn't a solution

 

So getting back to my recommendation.. Ravenol seems safe to use in the 360 and 430 based on manufacturer literature..be curious which oil was used in the failed transmission.. like i would guess a Mobil 1 sync gear oil could cause that but a Ravenol and or a Eni rotra lsx wouldn't

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What possible evidence do you have for that wild conclusion?

 

Just based on manufacturer literature.. that is why I would love to hear which oil was used in the failed transmission

Also I have a few people monitoring oil analysis if that helps

Other then the manufacturer literature, oil analysis and the real life reason for sync break down (which oil) what else can someone go by

I also believe red line makes that claim as well - brass safe

So as i mentioned if we can see which oil was used in the various transmission you are rebuilding ..it may give us a clue ..

Additionally - Mobil 1 sys not to use/ does not recommend in a manual transmission ..

So that's how I came up with my recommendation .. but , as you will say, that my recommendations are only based on the info i can get from manufacturers and so far no one using Ravenol in my circle has had sync failure ( doesn't mean much ..small time and sample)

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