Diff. Fluid
- Thread starter GRed
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Vehicle? Use? Age of old fluid? OEM recommendation?
Miles on the current diff fill?
Kestas
Staff member
If you're not sure when it was last changed, go ahead and change it. The same holds true for all fluids and filters for a newly purchased used vehicle. This will give you a starting point for future maintenance.
even though it smells good and looks good.. could that be deceiving ??? so change it anyways?? I have a service manual/maintenance for it. it indicates the 1st 18k then it doesn't say after that. How often is it safe to do so?? so go with every 20k??
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Gear oil is something that never gets changed. I'd say it likely was never changed.
Originally Posted By: GRed
even though it smells good and looks good.. could that be deceiving ??? so change it anyways?? I have a service manual/maintenance for it. it indicates the 1st 18k then it doesn't say after that. How often is it safe to do so?? so go with every 20k??
I ... uh ... don't think gear oil ever smells good.
Originally Posted By: GRed
even though it smells good and looks good.. could that be deceiving ??? so change it anyways?? I have a service manual/maintenance for it. it indicates the 1st 18k then it doesn't say after that. How often is it safe to do so?? so go with every 20k??
I ... uh ... don't think gear oil ever smells good.
If there's a plate to remove you can really get in there and clean the diff. If it's really clean at 70.8K---good. Kira
I would go with Amsoil SVG. Probably the best there is. Get the additive from the Dodge dealer for limited slip and add it. The Amsoil website will tell you the Dodge part number and how much. I needed to add 2 containers for my Dodge Ram 2500.
If you don't get smell from gear oil then you need to visit doctor and not change gear oil.
Originally Posted By: GRed
Is it safe to say that if the fluid smells & looks good means you don't have to change it out. or should it just be changed??
Some 10 years ago, I would have changed it for peace of mind as suggested by Kestas above.
Today, I wouldn't change a diff oil until it observes mild discoloration AND mild stinking smell.
Is it safe to say that if the fluid smells & looks good means you don't have to change it out. or should it just be changed??
Some 10 years ago, I would have changed it for peace of mind as suggested by Kestas above.
Today, I wouldn't change a diff oil until it observes mild discoloration AND mild stinking smell.
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Originally Posted By: GRed
Originally Posted By: Ethan1
When you buy a used truck, it's safe to assume that mileage on odometer = mileage on diff oil
Just thought one could tell
A UOA is the only way to know the condition of the oil. To be honest, unless you are able to just pull a sample (i.e. there is a drain plug on the axle or you siphon some out through the fill hole), it would not be worth it. Even if you can pull the sample, you will likely spend about 50% of the cost of new oil to test it, so if there is a question about its condition you may as well change it.
Originally Posted By: Ethan1
When you buy a used truck, it's safe to assume that mileage on odometer = mileage on diff oil
Just thought one could tell
A UOA is the only way to know the condition of the oil. To be honest, unless you are able to just pull a sample (i.e. there is a drain plug on the axle or you siphon some out through the fill hole), it would not be worth it. Even if you can pull the sample, you will likely spend about 50% of the cost of new oil to test it, so if there is a question about its condition you may as well change it.
Even if it looks and smells like new gear oil, there is probably a large amount of wear metal at the bottom of the housing.
Almost nobody changes gear oil unless some repair has been made in that area.
I suggest removing the differential pan, blasting everything clean with brake cleaner, then reinstalling the pan and refill.
Know the viscosity of oil that is specified, and if it has a limited slip differential. If there is a limited slip differential, either buy oil that already has the LS additives, or buy oil and additives separately.
I am guessing that this vehicle takes 75w140 syn. Valvoline and M1 are easy to find, sell at a low price, and already have LS additives.
Almost nobody changes gear oil unless some repair has been made in that area.
I suggest removing the differential pan, blasting everything clean with brake cleaner, then reinstalling the pan and refill.
Know the viscosity of oil that is specified, and if it has a limited slip differential. If there is a limited slip differential, either buy oil that already has the LS additives, or buy oil and additives separately.
I am guessing that this vehicle takes 75w140 syn. Valvoline and M1 are easy to find, sell at a low price, and already have LS additives.
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