I had my oil changed the other day by one of those 10 minute places and they told me the rear diff was a quart low and was very dirty. It was suggested I contact the Dealer to have it checked out. I called the Dealer and explained to him what the problem was and was told I had a leak and to bring it in. I said there were no spots under the truck and that I had just rotated the tires, but they insisted there must be a leak. They checked it out and could find nothing, said its all good and sent me on my way.


Has anyone had a similar thing happen?? We did just get back from a 3,000 mile round trip. pulling our trailer. Could it have gotten hot enough to cook off that much oil??

Almost all of them come factory, low.

I agree. GM says they can be up to 40mm below the hole. That's about a quart in my 11 1/2" diff. and that is also exactly where I found it when mine arrived on the hauler from the factory. I topped it off and IMHO your dealership should've done it before you took delivery as well...http://www.dieselplace.com/forum/smileys/Big Smile.gif


Ed

One thing about the 04's is that the fill spec for them is only 3 qts, that would put the level nearly an inch below the hole. This is considered normal. 01-03 capacity was just a nick shy of 4 qts.. funny huh? They didnt change the axle anyhttp://www.dieselplace.com/forum/smileys/Ermm.gif

So did the dealer actually change the differential oil, or did they they just check it? Has it ever been changed? You don't mention how many miles are on your truck, but if it hasn't been changed, it needs to be, especially after a 3,000 mile tow. My rear diff fluid was 1 1/2 quarts low & very dirty when I changed it at 5,000 miles.

Just in case you haven't read this: hoot's diff post (http://www.dieselplace.com/forum/forum_posts.asp?TID=1244&PN=1)

I had the very same thing with mine. I went down to the local dealer and spoke with a service tech that was under a truck at the time a told him about the low level. He said " with synthetic oil it should be about 30 mm under the fill hole". On the truck he was working on he also showed me a blue metal tag on the side of the rear end that said that very same thing. Mine does not have that blue tag so I went ahead and topped it off.

I think the manual says 5/8" to 1 5/8" below the fill hole is normal level. Must be GM's way of saving money by filling it to the lowest level (almost 1 qt difference from upper level). Do the math: 1 Qt. less oil per truck at $5 per Qt. times 1 million trucks a year. That's a $5 million saving per year (even if the only pay $1 per Qt., still quite a savings).

No the dealer didn't change the differential oil, and it was the second oil change I have had, they never mentioned the rear dif being low the first time. My truck has about 6,500 miles on it now. I thought the reccomended differential change was around 50,000 miles.

KAMPZITE,

I'm guessing that it really wasn't "low" per se to begin with - just at the lower acceptable level. If you're not seeing evidence of a fluid leak anywhere near the diff. then all is probably OK. I'd top it off to the "upper" allowable level (check your owners manual and it will tell you the proper level) and monitor it for a while. I cut a thin strip of sheet metal, bent it at a 90 degree angle and marked it in 1/2" increments from the bend to use as a dipstick thru the filler hole to see how far below the filler cap the level actually is. My guess is that you are fine.

but at 6500 miles it does need to be changed soon

but at 6500 miles it does need to be changed soon

As he said - if you haven't changed it yet - change it soon to get all the junk out from break-in - then you are good to go for awhile and just monitor the level until you are satisfied there is no problem

Fore more info from Eaton, the OEM of the Rear Diff, see the post by TxDoc in the following topic.


Rear End Service (http://dieselplace.com/forum/forum_posts.asp?TID=2643&KW=txdoc+rear+diff)


Also see


Differential Lube (http://dieselplace.com/forum/forum_posts.asp?TID=8341&KW=txdoc+rear+diff)


http://www.dieselplace.com/forum/smileys/Geek.gif

One thing about the 04's is that the fill spec for them is only 3 qts, that would put the level nearly an inch below the hole. This is considered normal. 01-03 capacity was just a nick shy of 4 qts.. funny huh? They didnt change the axle anyhttp://www.dieselplace.com/forum/smileys/Ermm.gif


Eric,


Do you think GM changed the spec to reduce the chance of leaking axel seals? The drivers-side seal (http://community.webshots.com/photo/65684589/139080723yFaWcq) on my 03 leaked ...Dealer replaced the seal along with new e-brake shoes at 25kmiles under warranty ... I had changed the fluid at 5k to M1 75W90 ... Per the 03 4qt spec It was about a quart low when I changed out the original fluid ???


http://www.dieselplace.com/forum/smileys/Geek.gif