Check Your Rear...Fluid

[Inspector 17]

After reading a post on here I asked the service manager at my dealer to change out my rear fluid while I had my car there for some other work. He looked at me somewhat oddly when I told him the car had 4500 miles on it. He said ok. When I returned to pickup the car I asked him about it. He laughed and said that the service tech looked at him kind of weird when he told him to change it out. However, he did say that there was a fair amount of "junk" on the plug and the fluid didn't look great. Nothing major, just some shaving sludge. I just wanted to post this as a note to everyone. Just might be a good idea to check your fluid and do a change out if you have the time/money.

[superstockcam]

I'm doing mine after I hit 5000 miles next week, at 2500 miles the oil from the rear looked like it came out of the Clampetts model A! Trans didn't look bad so I'm not doing it till 10k "2014" lol

[SSOOCH]

The "gunk" is an inhibitor in the fluid that is normal. Now with that said, I changed out my rear diff fluid at 2500 miles!

[Stingr69]

The factory uses a colored gear setup paste that will make the fluid off-color in a new differential. That color would go away with more miles but it does not hurt anything to change the fluid early. It does give you peace of mind even if it was not needed.

-Mark.

[Angrybird 12]

Originally Posted by superstockcam

I'm doing mine after I hit 5000 miles next week, at 2500 miles the oil from the rear looked like it came out of the Clampetts model A! Trans didn't look bad so I'm not doing it till 10k "2014" lol

Just FYI, the Clampetts truck was an Oldsmobile, not a Model A.

[BigMatt]

yep I changed mine at 1500 miles, the magnet was full of shavings.

[Inspector 17]

Originally Posted by SSOOCH

The "gunk" is an inhibitor in the fluid that is normal. Now with that said, I changed out my rear diff fluid at 2500 miles!

I think there is a appreciable difference between "gunk" and shavings. What I was referring to when I said "junk" was actually metal shavings on the plug.

Originally Posted by Skyman 08

Just FYI, the Clampetts truck was an Oldsmobile, not a Model A.

Good call.

[Angrybird 12]

Well that is what the magnet is there for to collect the shavings that happen during break in and to keep them out of the gears.. and another reason GM has the specific break in instructions for your car to prevent excessive shavings... for those that are doing a drive it like you stole it from day one, you may be seeing more evidence of this than others are...

[Inspector 17]

Originally Posted by Skyman 08

Well that is what the magnet is there for to collect the shavings that happen during break in and to keep them out of the gears.. and another reason GM has the specific break in instructions for your car to prevent excessive shavings... for those that are doing a drive it like you stole it from day one, you may be seeing more evidence of this than others are...

Completely agree that's what the magnet is for. However, I baby my car and I think the build-up warrants people doing a rear fluid change sooner than you might normally (if you have the means).

[Angrybird 12]

Originally Posted by camaropete

Completely agree that's what the magnet is for. However, I baby my car and I think the build-up warrants people doing a rear fluid change sooner than you might normally (if you have the means).

I bet that if you were to examine all cars after the same period of time you would find the same shavings inside.. I bet if you folloed the GM maintenance schedule you would be ok.. besides if it does go out in the first 100,000 miles it is covered...... i think too many are overreacting...

[Inspector 17]

Originally Posted by Skyman 08

I bet that if you were to examine all cars after the same period of time you would find the same shavings inside.. I bet if you folloed the GM maintenance schedule you would be ok.. besides if it does go out in the first 100,000 miles it is covered...... i think too many are overreacting...

Perhaps. But what is the harm in replacing the fluid and cleaning off the plug?

[SSLarry]

Originally Posted by Stingr69

The factory uses a colored gear setup paste that will make the fluid off-color in a new differential. That color would go away with more miles but it does not hurt anything to change the fluid early. It does give you peace of mind even if it was not needed.

-Mark.

So, if GM puts in an inhibitor for a reason, then what would be the benefit of replacing that inhibitor way early (say, under 5000 mi) ? Why not let the inhibitor do it's job and replace the diff oil when recommended?

Just curious if we are actually hurting our cars by replacing that 'special' factory blend on a new diff.

[Stingr69]

Originally Posted by SSLarry

So, if GM puts in an inhibitor for a reason, then what would be the benefit of replacing that inhibitor way early (say, under 5000 mi) ? Why not let the inhibitor do it's job and replace the diff oil when recommended?

Just curious if we are actually hurting our cars by replacing that 'special' factory blend on a new diff.

I know nothing about any "inhibitor". The set up paste is just part of the assembly process and it is what gives the fluid a strange color. The only reason I posted about it was to offer an explanation for the strange looking fluid. The off-color fluid complaint is known to GM so they gave that response so service departments can respond to owners who inspect the rear axle lubricant at earlier service intervals. The paste serves no usefull purpose after the differential is assembled. It is just "in there" causing no problems other than appearance.

I will plan on changing my diff fluid soon. It has 8,000 miles and some drag strip runs on it. The manual gives some advice here so I plan on following it.

-Mark.

[Angrybird 12]

Originally Posted by camaropete

Perhaps. But what is the harm in replacing the fluid and cleaning off the plug?

Well spending money you don't need to spend for one...and I don't know about you but I don't have the money laying around any more to just spend it on things that may or may not provide any benefit...you can thank the poor economy for that..

As far as i know I haven't heard of anyone having a rear grear failure because they didn't change the fluid yet...if they start showing up then it would be a benefit.. but until then I will go by GM's recommendation.

BTW My car is used for just general all around driving, not drag racing, if you do plan on running it that hard I would cange it often.. but for normal use I feel it is a waste of time and money...and I have owned many cars and trucks and never had a rear gear failure following the Manufacturers instructions...