I do not remember exactly, but ca 20-25$. I live in FD and bought it in Poland (EU).

 

I used 75W90 rear axle oil because Motul not manufactured 75W85. They have two types of the oil: Gear 300 75W90 and Gear 300 LS 75W90. The "LS" version is suitable for rear differential equipped with Limited Slip system.

 

.


Watching this thread I see that some ppl read into A SUGGESTION vs A REQUIREMENT when it come to products. Then you have a mindset of a PERSONAL PREFERENCE added into the mix. Different products only give a certain amount of 'specs', and then it is VERY confusing for laypeople. All I can say forward, is this type of thread will be a never ending stream of point/counterpoint with no end in sight. Good luck!


.

 

thank you guys who contribute with polite and positive comments, data and experience. this is what makes this forum great.
keep posting and watching.

 

regarding the subject of this thread, the factor that is of most relevance is that oil for gears is regulated by a standard created specifically for them, and differs dramatically from the standard for oil for engines: for engines says:. "in an example for SAE viscosity grades, lets say 5w25, the former grades denote a multigrade engine oil's low-temperature properties (W denoting "winter"), whereas the latter grades denote an engine oil's properties at the operating temperature of an engine''
the 1 for gears says: "SAE J306 is a standard that defines the viscometric properties of automotive gear oils. It is maintained by SAE International.[1] Key parameters for this standard are the kinematic viscosity of the gear oil, the maximum temperature at which the oil has a viscosity of 150,000 cP, and a measure of its shear stability through the KRL test."
and:Multigrade SAE gearbox oil grades include two numbers separated by a ‘W’ (75W140, for instance), with the initial number before the ‘W’ indicating performance at 0°C and the number after showing the lube’s performance at 100°C. As with monograde oils, the higher the number, the greater its viscosity.
hence the large difference of numbers that, if not knowing this, just seems incomprehensible.
and once again, thanks to the contribution of pizzaguy, who enlightened us with this valuable information.

 

the chart below is more complete and clear than the 1 we saw before.
and there is so much to learn from it.

 

I found this link fun to read:
https://www.thelubricantstore.com/un...ty-grade-chart

I guess 75W90 gear lube is similar in viscosity to my old 20W50 engine oil, which I ran for 150,000 miles in my 4.3L Vortec engine.
(The Lubricant Store is where I got my Mobile 1 5W50 I ran in the Graphite Crossfire in the summer heat - could not get it any where else.)

 

See below. I tried everything and the MB fluid from Rob was clearly the best.

https://www.crossfireforum.org/forum...-post4677.html

 

on post 45 i presented data on how the sae figures compare depending if for engine oil or gear box oil. what is mentioned is that for engines, the temp for the high point is the operating temp of the engine, and on gears is 100 C degrees (212 F). but the operating temp is not mentioned and i didnt know it, so searched and found this somewhere:
"Now that I have a engine performance data logging computer installed in the car I monitor many of those parameters when I'm at the track... The cooling system seems to work really well on this car... I've run it on the track in 105 degree weather and the highest ECT (engine coolant temp) logged was only 212 degrees... That was represented on the gauge at the midway point... From a cold start sitting at idle it will run about 183-185 degrees... It seems that the fan sensor trips at about 190 degrees.." so this is engine oil temp.
in other words:
sae figures shown for the numbers after w are:
for engine oils: 212 f;
for gear oils: 212 f
so are measured at the same temp.
but, is it possible that the gear box may run at 212 f degrees? that hot? any1 has data on this?

__________________

 

just in case you wonder whats the difference between synthetic and mineral oils viewed from the perspective of germany's technology:
https://www.bizol.com/company/educat...tic-motor-oil/
which is the way ours xf are made.

 

regarding which part uses which oil, the manual specifies:
1-engine: only synthetic engine oils approved to MB 229.3 or MB 229.5, such as Mobil 1 SAE 0W-40. should say: engine oil SAEJ300 0W40
2-automatic transmission: only use ATF approved to MB 236.10, MB 236.12 synthetic dextro III transmission fluid
3-manual transmission fluid: only use fluid approved to MB 236.2. SAE 5W-20 engine oil, meeting API SL or GF-3. should say: engine oil SAEJ300 5W20
4-rear axle fluid: only synthetic SAE 75W85 axle lubricant that meets MB 231.1 should say: rear axle oil SAEJ306 75W85
so:
1- engine uses engine oil (of course);
3-manual transmission also uses engine oil of a little different viscosity.
4-rear axle uses gear box oil. it is another kind of oil. it is NOT engine oil (the specification is SAE 75W85). the manual does not specify if this is the same kind of oil or not as the engine. in reality, it is different kind of oil
the problem is that, as mentioned before, SAE is not just SAE. there are 2 different classes.
engine and transmission use SAE J300, and rear axle uses SAE J306, and this should be mentioned in all cases, because the numbers are so far apart, that trying to use the wrong specification means havoc to the part. (it is all clear on the chart provided by pizzaguy-see post 47)
(2-with automatic transmission, the lubricant is transmission oil specific for it).
in conclusion:
1- engine and transmission use engine oil (although of different viscosity-but not much)
2-rear axle does not use engine oil; uses a different kind of oil, designed specifically for gears.
3-automatic transmission uses another kind of oil for transmission, that is specific for it.

 

 

Now that's Funny !!!