Is Maxlife 75W-80 GL4 MTF safe for yellow metals

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Originally Posted By: FordCapriDriver
Last question i promise


LoL
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GL4 was made for that very purpose.You are good to go. Its especially good in front wheel drive cars as is Honda MTF or Redline MTL which I loved in my Sunfire GT.
 
I also thought that GL4 was good for yellow metals , but i also read later that some GL4 oils may still have the sulphur additives that are corrosive to brass parts, thanks anyway
 
Originally Posted By: FordCapriDriver
I also thought that GL4 was good for yellow metals , but i also read later that some GL4 oils may still have the sulphur additives that are corrosive to brass parts, thanks anyway


Those are typically marked GL-4/GL-5.
 
At first i was going to put Castrol EP 80W in the gearbox but it's too expensive at 13 Euro a Liter , i can get Maxlife 75W-80 for half of that so.... isn't Maxlife also meant for high mileage geraboxes? in that case it should be good for mine with 305.000 Miles and 41 years in the car with barely any fluid changes
 
Originally Posted By: FordCapriDriver
At first i was going to put Castrol EP 80W in the gearbox but it's too expensive at 13 Euro a Liter , i can get Maxlife 75W-80 for half of that so.... isn't Maxlife also meant for high mileage geraboxes? in that case it should be good for mine with 305.000 Miles and 41 years in the car with barely any fluid changes


The Maxlife 75W80 (KV@40*C- 52 cSt; KV@100*C- 9.4 cSt) is far weaker than Castrol EP 80W (of KV@40*C- 94 cSt ; KV@100*C- 9.9 cSt)in your Caprice at typical operating temperature.
I'd a hunch that your winter ambient temperature is unlikely to encounter shiftability issue, this high mileage Caprice manuals should really consider a xxW90, preferably a shear-stable 80W90 of stronger KV's likely available at competitive price.
JMHO.
 
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Capri , not Caprice , that's a Chevrolet, i have some Ford 75W-90 GL-4 gear oil that is approved for gearboxes with yellow metals such as brass synchros, might use that then , i have 1 Liter left so i only need another bottle
Kv of 15.0 cst
 
Originally Posted By: FordCapriDriver
I also thought that GL4 was good for yellow metals , but i also read later that some GL4 oils may still have the sulphur additives that are corrosive to brass parts, thanks anyway


Wherever you read that it is wrong.

A dedicated MTF with a GL-4 protection rating between a viscosity of 8.0 cSt to 10.0 cSt at 100C is what you need.
 
Originally Posted By: FordCapriDriver
Maxlife 75W80 falls right into that category , shame i can't use the bottle of Ford GL4 75W90 i have left over though, it only takes 2 liters


This Maxlife 75W80 is closer to ISO 46 vs
Castrol EP 80W's ISO 100 gear oil viscosity grade......
miles apart when one considers components wear protection.
A typical 75W90 is a thicker ISO 100 than Castrol EP 80W.
Just my 2 cents.
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Originally Posted By: zeng
Originally Posted By: FordCapriDriver
Maxlife 75W80 falls right into that category , shame i can't use the bottle of Ford GL4 75W90 i have left over though, it only takes 2 liters


This Maxlife 75W80 is closer to ISO 46 vs
Castrol EP 80W's ISO 100 gear oil viscosity grade......
miles apart when one considers components wear protection.
A typical 75W90 is a thicker ISO 100 than Castrol EP 80W.
Just my 2 cents.
blush.gif


So i COULD use the Ford oil i have left over? It's GL4 an d approved for older transmissions with brass components
The gearbox is 41 years old and has 490.000 Kms on it so could it beenfit from a thicker oil?
Man gear oil is proving to be confusing...
 
Originally Posted By: FordCapriDriver
So i COULD use the Ford oil i have left over? It's GL4 an d approved for older transmissions with brass components
The gearbox is 41 years old and has 490.000 Kms on it so could it beenfit from a thicker oil?
Man gear oil is proving to be confusing...


Surely, you could.
Under existing scenarios, I would think you should .....as you already have it and your aged transmission is a Ford.
However my limited understanding of Ford 75W90 MTF is it's weak KV@40*C and could be very shear-prone.
I somehow feel the 'weak' Maxlife 75W80 may have some VII and is a no-no for your very-very high mileage and aged transmission.
The Castrol EP 80W and a typical mineral 80W90 (that provides strongest benefit among the crowd here,to your aged transmission) are shear-stable though.
JMHO.
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Originally Posted By: FordCapriDriver
Well the Ford 75w90 has a Kv pf 15.0cst so if it shears down it will still be a 85 or 80w, the Castrol EP80 is also about twice the price


If you are referring to high oil operating temperature where oil sump temperature is 80ish to 90ish,as in the case of engines, and conrod oil temp at 130ish ..... then your points above are rock solid.
However , in gear train drives that may not be the case ..... hence KV@40*C is to be considered as well as shearing.IMHO.

Yep,FCD. Ford 75W90 should be your pick here.
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Originally Posted By: FordCapriDriver
Maxlife 75W80 falls right into that category , shame i can't use the bottle of Ford GL4 75W90 i have left over though, it only takes 2 liters


Then use 1 L of the above with 1 L of the MaxLife 75W80.

Most dedicated MTF's of 75W90 are designed for an approx. 14.0 to 15.0 cSt@100C thickness.


Originally Posted By: zeng
However my limited understanding of Ford 75W90 MTF is it's weak KV@40*C and could be very shear-prone. I somehow feel the 'weak' Maxlife 75W80 may have some VII and is a no-no for your very-very high mileage and aged transmission.


Supposedly weak, how? All gear oils have a specified amount of Viscsoity Index Improver, but that doesn't make them "weak."
 
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