So who is running synthetic in their rearend?

[5spd GT]

I'm going to run full synthetic all the way throughout my car and I'm going to start with the transmission and rear-end. Probably Royal Purple to stay "matching"...

What weight fluid do you guys use?

I'm in Arkansas (max temps are 110F and low is -10F).

Thanks for the replies...just curious what others are running in thier rears

 

[86bluecobra]

i run synthetic in my rear end. i bought castrol i forget the wieght.

 

[1EVIL88VERT]

i run royal purple 75-w90...i think thats it....pretty sure....ok i know it's royal purple..

 

[5spd GT]

Thanks for the replies...any more "solid" weight numbers

I'm going to regasket it when I do the rearend...

 

[jgressley2003]

I've got 75w90 Valvoline Full Synthetic in mine

 

[8950HO]

Mobil 1, 75W-90.

 

[Modular2v]

most of the time the girlfriend just wants a LOT of K.y.

 

[tb9050lx]

I'm going to run full synthetic all the way throughout my car and I'm going to start with the transmission and rear-end. Probably Royal Purple to stay "matching"...

What weight fluid do you guys use?

I'm in Arkansas (max temps are 110F and low is -10F).

Thanks for the replies...just curious what others are running in thier rears

75 140 motorcraft synthetic

 

[352Ford2]

most of the time the girlfriend just wants a LOT of K.y.

My girlfriend doesn't need KY.




really though I have 75w 140 AMS oil

 

[Henceforward]

I am running Amsoil 75W-90 Gear Oil, but it has only been in the case for 400 miles, I just had 3.73 gears installed over the break.

 

[vristang]

I currently have Redline in mine. At the next change I will switch to Mobil 1 for availability reasons.

I don't remember the weight, but I would recommend sticking with the factory callout.

jason

 

[Lemonade]

Lems

 

[5spd GT]

So I see 75w-90 and 75w-140...pretty broad spectrum there in terms of the numbers

Stupid question: So gear oil is the same "synthetic oil" as rearend oil?

 

[vristang]

So I see 75w-90 and 75w-140...pretty broad spectrum there in terms of the numbers

Stupid question: So gear oil is the same "synthetic oil" as rearend oil?

A rearend has gears.
Is there a difference between the official definitions of these terms?

For weight, I still say use the factory suggestions.
The Chiltons or Haynes manuals should have it.
I'd look it up myself, but my books are an hours drive away.

 

[352Ford2]

So I see 75w-90 and 75w-140...pretty broad spectrum there in terms of the numbers

Stupid question: So gear oil is the same "synthetic oil" as rearend oil?

I think you are talking aboud hypoid gear oil, and yes the gears in our rear ends are hypoids , so yes you want hypoid gear oil. So nobody asks, they are calleds hypoid gears because if you map their rotaional pattern it makes a hyperbola (sp?). The reason you want special gear oil for this type of gear is the contact pattern of the teath.

if you are talking about synthitec vs coventional, it is just how it is made, syn is make by us and conv is make by nature and refined by us

 

[HISSIN50]

I will note that 75-140 synthetic is recommended by Ford in some 8.8" rear ends. Because of the superior (to dino 75/80W-90) cold flow, I will use it next change, I think (or one bottle of the thicker stuff and the rest will be the thinner stuff - not sure yet).

 

[Henceforward]

Thanks for the replies...any more "solid" weight numbers

I'm going to regasket it when I do the rearend...

You don't have to use the gasket, just use RTV.

 

[bill302]

factory specs for 8.8 rearend fluid is 3.75 pts. hypoid gear lubricant sae 80 or 90 and 4 oz. of friction modifier c8az-19b546-a or equivalent.

 

[5spd GT]

HenceForward - That will save me some money...I might just do both

vristang - I was just looking at some of Redline's products and was seeing they had "shockproof" gear oil and was just seeing if there was a difference in them. My mistake on the wording...I have found what I needed.

JT - You always make the wise choices And give the wise advice...

Oh and I'm going to check the Royal Purple's instructions on if it has to have friction modifier added with it...

 

[352Ford2]

You don't have to use the gasket, just use RTV.

Use a gasket, for god sakes, there is only one axle that you should use gasket sealer for that and that is a dana 44 TTB in the front of 80's ford trucks, and the only reason you should use it then is becasue you have no choice.