Do I have this right. GL5 yellow metal.

[dnastrau]

Originally Posted By: expat
Just for clarity.
I have a Diff in a RWD car that has Yellow metal thrust washers. The original spec is for GL4 which is a little difficult to come by.

My understanding is: GL4 is largely considered obsolete and for 'Rear ends' GL5 is now the norm.
However, GL5 may incorporate twice the sulphur EP additive of GL4 which may cause problems with yellow metal components.
But this has not too much an issue, as yellow metal is now seldom used in modern rear ends.

Some GL5's may have Buffers to counter the effects on yellow metal. But there is no requirement within the GL specification for this. ie. It is up to the manufacturer, and their 'word' it is yellow metal safe.


As a point of clarification: I don't think GL-5 replaced/superseded GL-4. They are just different specifications where GL-5 cannot replace GL-4 in cases where yellow metals are used.

GL-4 is harder to find but any good auto parts store should have it or be able to get it easily.

Andrew S.

 

[yvon_la]

http://www.mobil.com/USA-English/Lubes/P...n_Fluid_50.aspx

Mobil Delvac Synthetic Transmission Fluid 50 meets or exceeds the requirements of the API service MT-1 EP gear oil service classification and is recommened by ExxonMobil for use in transmissions and gear cases where API Service GL-1 through GL-4 gear protection is required.

 

[Whitewolf]

For what it's worth and just to add some further thoughts to this discussion!
Have any of you taken a look at tractor fluids? If you are interested in GL-4 level performance the common UTTOs based on either Afton or Lubrizol chemistry meet that.

 

[Kamele0N]

Just find GL5 that is yellow metal friendly..

GL4+

GL4/5

GL5 + MT-1

 

[GiveMeAVowel]

Originally Posted By: spk2000
Yellow metal is a phosphor coating that increases rust resistance. Not as good as galvanizing but better than bare metal.

Not sure what is in it that makes it not yellow safe though. Must have a reaction with the phosphor coating.


Wrong.

 

[GiveMeAVowel]

The interesting thing to me is that if you go to Europe you will find tons of GL-4 spec fluids from all major brands. Castrol,
Shell, Valvoline, BP, Liqui Moly, ect.

 

[MolaKule]

Originally Posted By: expat
Just for clarity.
I have a Diff in a RWD car that has Yellow metal thrust washers. The original spec is for GL4 which is a little difficult to come by.

My understanding is: GL4 is largely considered obsolete and for 'Rear ends' GL5 is now the norm.
However, GL5 may incorporate twice the sulphur EP additive of GL4 which may cause problems with yellow metal components.
But this has not too much an issue, as yellow metal is now seldom used in modern rear ends.

Some GL5's may have Buffers to counter the effects on yellow metal. But there is no requirement within the GL specification for this. ie. It is up to the manufacturer, and their 'word' it is yellow metal safe.


I think what spk2000 was referring to was steel parts with a phosphate coating that makes them look yellow and there are parts like that.

However, what the OP needs to determine is: are those thrust washers really bronze alloys or are they phosphate coated steel alloys?

A pocket knife scraping should tell him which it is.

 

[widman]

Considering the fact that I'm helping a friend locate (or try to) the brass thrust washers for his differential (we took it apart Wednesday), I'd stick with the manufacturer's recommendations.

 

[Whitewolf]

I'm thinking that you must have read the thread just below that talks about available GL-4 products?