Differentail fluid efficacy
 

Is it possible to determine if differential fluid is losing efficacy?
What is the measure? Viscocity? Can efficacy be quantified easily?
Actually I would be interested in knowing if there are quantifiable
measures for the efficacy of other fluids, assuming they are not
contaminated or burnt. Thank you.

P.S. I changed the front and rear differentail fluids in my Jeep WJ
2004, AWD, first time after 50K miles. I saw that the old fluid was
quite viscous, only slight brownish, not horribly bad smelling, and
did not seem to have any metal shavings. I am starting to wonder if I
could have done the change after a few more 10K miles...

Re: Differentail fluid efficacy
 

If they are limited slip differentials you want to follow the change
intervals religiously. If they are not the fluid may last the life of the
vehicle---but who wants to take chances?

I would recommend synthetic next time, to cut down on friction losses in the
winter. This is one place where synthetic might be economically viable.

In addition to viscosity you care about something called "shear strength",
which is a function of additives. I don't know how you would determine that
in used differential oil. You also care about water contamination. If you
even suspect that you put the rear axle under water, at least check it for
milkshake consistency. If it rains a lot where you are, level and
consistency checks should be somewhat more frequent.

Cheers,

Earle

"stilllearning" <shahswim@yahoo.com> wrote in message
news:1179687700.789370.304160@y2g2000prf.googlegro ups.com...
> Is it possible to determine if differential fluid is losing efficacy?
> What is the measure? Viscocity? Can efficacy be quantified easily?
> Actually I would be interested in knowing if there are quantifiable
> measures for the efficacy of other fluids, assuming they are not
> contaminated or burnt. Thank you.
>
> P.S. I changed the front and rear differentail fluids in my Jeep WJ
> 2004, AWD, first time after 50K miles. I saw that the old fluid was
> quite viscous, only slight brownish, not horribly bad smelling, and
> did not seem to have any metal shavings. I am starting to wonder if I
> could have done the change after a few more 10K miles...
>

Re: Differentail fluid efficacy
 

If they are limited slip differentials you want to follow the change
intervals religiously. If they are not the fluid may last the life of the
vehicle---but who wants to take chances?

I would recommend synthetic next time, to cut down on friction losses in the
winter. This is one place where synthetic might be economically viable.

In addition to viscosity you care about something called "shear strength",
which is a function of additives. I don't know how you would determine that
in used differential oil. You also care about water contamination. If you
even suspect that you put the rear axle under water, at least check it for
milkshake consistency. If it rains a lot where you are, level and
consistency checks should be somewhat more frequent.

Cheers,

Earle

"stilllearning" <shahswim@yahoo.com> wrote in message
news:1179687700.789370.304160@y2g2000prf.googlegro ups.com...
> Is it possible to determine if differential fluid is losing efficacy?
> What is the measure? Viscocity? Can efficacy be quantified easily?
> Actually I would be interested in knowing if there are quantifiable
> measures for the efficacy of other fluids, assuming they are not
> contaminated or burnt. Thank you.
>
> P.S. I changed the front and rear differentail fluids in my Jeep WJ
> 2004, AWD, first time after 50K miles. I saw that the old fluid was
> quite viscous, only slight brownish, not horribly bad smelling, and
> did not seem to have any metal shavings. I am starting to wonder if I
> could have done the change after a few more 10K miles...
>

Re: Differentail fluid efficacy
 

If they are limited slip differentials you want to follow the change
intervals religiously. If they are not the fluid may last the life of the
vehicle---but who wants to take chances?

I would recommend synthetic next time, to cut down on friction losses in the
winter. This is one place where synthetic might be economically viable.

In addition to viscosity you care about something called "shear strength",
which is a function of additives. I don't know how you would determine that
in used differential oil. You also care about water contamination. If you
even suspect that you put the rear axle under water, at least check it for
milkshake consistency. If it rains a lot where you are, level and
consistency checks should be somewhat more frequent.

Cheers,

Earle

"stilllearning" <shahswim@yahoo.com> wrote in message
news:1179687700.789370.304160@y2g2000prf.googlegro ups.com...
> Is it possible to determine if differential fluid is losing efficacy?
> What is the measure? Viscocity? Can efficacy be quantified easily?
> Actually I would be interested in knowing if there are quantifiable
> measures for the efficacy of other fluids, assuming they are not
> contaminated or burnt. Thank you.
>
> P.S. I changed the front and rear differentail fluids in my Jeep WJ
> 2004, AWD, first time after 50K miles. I saw that the old fluid was
> quite viscous, only slight brownish, not horribly bad smelling, and
> did not seem to have any metal shavings. I am starting to wonder if I
> could have done the change after a few more 10K miles...
>

Re: Differentail fluid efficacy
 

If they are limited slip differentials you want to follow the change
intervals religiously. If they are not the fluid may last the life of the
vehicle---but who wants to take chances?

I would recommend synthetic next time, to cut down on friction losses in the
winter. This is one place where synthetic might be economically viable.

In addition to viscosity you care about something called "shear strength",
which is a function of additives. I don't know how you would determine that
in used differential oil. You also care about water contamination. If you
even suspect that you put the rear axle under water, at least check it for
milkshake consistency. If it rains a lot where you are, level and
consistency checks should be somewhat more frequent.

Cheers,

Earle

"stilllearning" <shahswim@yahoo.com> wrote in message
news:1179687700.789370.304160@y2g2000prf.googlegro ups.com...
> Is it possible to determine if differential fluid is losing efficacy?
> What is the measure? Viscocity? Can efficacy be quantified easily?
> Actually I would be interested in knowing if there are quantifiable
> measures for the efficacy of other fluids, assuming they are not
> contaminated or burnt. Thank you.
>
> P.S. I changed the front and rear differentail fluids in my Jeep WJ
> 2004, AWD, first time after 50K miles. I saw that the old fluid was
> quite viscous, only slight brownish, not horribly bad smelling, and
> did not seem to have any metal shavings. I am starting to wonder if I
> could have done the change after a few more 10K miles...
>

Re: Differentail fluid efficacy
 

Normally, axle fluid is not changed on a regular basis. If you have a
posi-type differential, then there may be a change schedule to follow.
The owners manual and D-C Factory Shop Manaul call for 80W90 (dino)
and recommend synthetic 75W90 for trailer towing....and there may be a
schedule if you tow on a regular basis. If you submerge the axle in
water (water has entered the diff) then you need to change the fluid
ASAP. Other than that, the stuff is supposed to last the life of the
vehicle....but there's nothing stopping you from changing it on a
regular basis.

mike
00XJ

Re: Differentail fluid efficacy
 

Normally, axle fluid is not changed on a regular basis. If you have a
posi-type differential, then there may be a change schedule to follow.
The owners manual and D-C Factory Shop Manaul call for 80W90 (dino)
and recommend synthetic 75W90 for trailer towing....and there may be a
schedule if you tow on a regular basis. If you submerge the axle in
water (water has entered the diff) then you need to change the fluid
ASAP. Other than that, the stuff is supposed to last the life of the
vehicle....but there's nothing stopping you from changing it on a
regular basis.

mike
00XJ

Re: Differentail fluid efficacy
 

Normally, axle fluid is not changed on a regular basis. If you have a
posi-type differential, then there may be a change schedule to follow.
The owners manual and D-C Factory Shop Manaul call for 80W90 (dino)
and recommend synthetic 75W90 for trailer towing....and there may be a
schedule if you tow on a regular basis. If you submerge the axle in
water (water has entered the diff) then you need to change the fluid
ASAP. Other than that, the stuff is supposed to last the life of the
vehicle....but there's nothing stopping you from changing it on a
regular basis.

mike
00XJ

Re: Differentail fluid efficacy
 

Normally, axle fluid is not changed on a regular basis. If you have a
posi-type differential, then there may be a change schedule to follow.
The owners manual and D-C Factory Shop Manaul call for 80W90 (dino)
and recommend synthetic 75W90 for trailer towing....and there may be a
schedule if you tow on a regular basis. If you submerge the axle in
water (water has entered the diff) then you need to change the fluid
ASAP. Other than that, the stuff is supposed to last the life of the
vehicle....but there's nothing stopping you from changing it on a
regular basis.

mike
00XJ

Re: Differentail fluid efficacy
 

Hi Mike,
FYI You might want to look at your manual and see what qualifies your
wagon to use the lube maintenance schedule "B":
http://www.----------.com/temp/01XJaxleDrain.pdf I've never owned a car that
the axle didn't have to be changed every twelve, or twenty four thousand
miles.
God Bless America, Bill O|||||||O
mailto:--------------------


"Mike" <meerkat23@bellsouth.net> wrote in message
news:1179967610.492538.233810@h2g2000hsg.googlegro ups.com...
>
> Normally, axle fluid is not changed on a regular basis. If you have a
> posi-type differential, then there may be a change schedule to follow.
> The owners manual and D-C Factory Shop Manaul call for 80W90 (dino)
> and recommend synthetic 75W90 for trailer towing....and there may be a
> schedule if you tow on a regular basis. If you submerge the axle in
> water (water has entered the diff) then you need to change the fluid
> ASAP. Other than that, the stuff is supposed to last the life of the
> vehicle....but there's nothing stopping you from changing it on a
> regular basis.
>
> mike
> 00XJ
>



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