A Car Maintenance Question

[ltt]

The last time we took our vehicle in for service, the dealership wanted to change the differential fluid.  We said no, as we were having other repair work done.  Come to find out, a few weeks later, I was having lunch with a group of friends and one needed a ride home as their car was at the dealership having some work done (same dealership by the way).  As I was giving them a ride, they were on the cell phone with the dealership and when they hung up, it was mentioned they wanted to change the differential fluid.  :(

So, my question is, does differential fluid need to be changed?  I can't even find anything in the owner's manual about it.

[frpeebles]

It depends on the vehicle. Most generic cars are front wheel drive with a transaxle in which the differential is located. These units are either permanently sealed or use the transmission oil as lubrication. Both my vehicles are this way. If you have a rear wheel drive vehicle chances are good your differential is separate from the transmission (This is the round part you see in the middle of axles on pickup trucks) and needs periodic maintenance. 4x4 vehicles will have one front and rear and a transfer case in the middle all of which have their own oil to change occasionally. All wheel drive vehicles have three differentials, two of which will need servicing.

FWIW this is a service that most people neglect for the life of the vehicle. Given this is the MMM forums I'd suggest doing it yourself on most vehicles that actually need it. It's typically very simple.

Transmission fluid (for autos and manuals alike) is more important, IMO.

[Cole]

If differential oil needs to be changed on your car it is usually around every 30-50k miles. I would do a quick Google search about changing differential oil on your car or go ask your local auto parts store.

[Syonyk]

What vehicle and how many miles? Ensure it has a separate differential fluid to change, otherwise find a new dealership.

It should be changed regularly. Differentials, especially on a truck, are expensive if they fail!  There's no harm and only a few dollars involved in changing it.  If you're doing a lot of heavy work, you can get differential covers with drain plugs and dipsticks to make changes easier.

[ltt]

It is an AWD with around 85,000 miles.  Dealership said front and rear would need to be changed and said it was around $130 or so for each.

[frpeebles]

Doesn't sound crazy. I'd still do it myself but that's a whole different road only you can chose to go down :)

[Syonyk]

A bit high, and you might be able to find an independent shop (NOT Jiffy Lube or similar!) willing to do it for less.

I really, really hate old gear oil, so I might pay someone to do it. But at 85k miles, it's worth doing.

[Spork]

It depends on the vehicle.  I've had vehicles that did not have a service schedule at all for the diff.  That said, it's not going to hurt to change it.

If you're going to do it yourself, you'll want an inexpensive pump to pump the oil in.  I generally use something like this:

http://www.amazon.com/Plews-55001-Lubrimatic-Standard-Bottles/dp/B000BQW5LK/ref=pd_sim_263_3/190-0577875-9863836

[mschaus]

As with engine oil and other maintenance items, read your owner's manual. It will have a schedule of what needs to be done when. The auto makers all have groups of engineers whose job it is to determine what these service intervals are to be best for the vast majority of users.

[m8547]

Do it yourself. It's as easy as an oil change, and the oil only costs a bit more than motor oil, but they charge 5x as much as an oil change! Same with transmission fluid. In my last car the transmission fluid was even easier than an oil change!

[Chris22]

It is an AWD with around 85,000 miles.  Dealership said front and rear would need to be changed and said it was around $130 or so for each.

$130 ea!!  Holy crap.  Yes, a non-FWD with a differential will need a fluid change.  In my car that has an LSD (limited slip differential) it takes less than a full $10 bottle of Mobil 1 gear oil.  I can change it in about 15 minutes.  makes it a lot easier if you buy a $5 fluid pump at Autozone/Harbor Fright or similar.  Gear oil smells so nasty that I throw the pump out each time instead of keep the stinky thing.  I do the fluid change every 2 years or so. 

[captainawesome]

I'll echo, go with what the manufacturer's maintenance schedule says. Most people can get away with that stuff because they cycle their cars out before they ever approach the failure point.  But if the recommended maintenance is 50k, and it has never been done, chances are it is a good idea to do it.  Find a good shop to do it, and they won't nickel and dime you. Just remember, they have to make a living too, so it will cost something.  Dealerships tend to be more because they pay for more overhead, convenience, coffee in the waiting area etc.  But I think some people forget that work isn't done for free.

[guitar_stitch]

What vehicle?  I know Hondas use a very special "Dual Pump" fluid for their AWD rear differentials due to the hydraulic nature of their operation.