I changed all my fluids to synthetic, including the front diff. I went to the dealer to buy the white vent cap and the parts guy asked me why I needed it. I told him and he said he never heard of that. He asked another parts guy and he hadn't either. They asked one of the techs and he said that it's not necessary unless it's leaking. What gives here. Is this one of those urban legend things. Or just another creative way for GM to separate me from another 25 of my hard earned dollars?

Your 03 should already have the white cap in it don't worry about it.

The 01 and 02 models with the black caps needed changing if switching to synthetic fluid.

Something about the way the vent is made didn't work well with synthetic's

Nope, I checked when I changed the fluid and it is black.

I heard the same thing about the black one leaking with synthetic, so I switched. The parts guys looked at me funny too.

Here's a pic of the difference. The white one has a metal vent too.
http://mysite.verizon.net/vze7z5f3/sitebuildercontent/sitebuilderpictures/frontdiffcover2.jpg

My 03 has the black vent, but I didn't change it when I switched to synthetic. No leaks yet...

syn supposedly eats part of it, the o ring IIRC, it will supposedly casue a bit of seepage. Some 03's have em and some dont, 03 is the cut off year IIRC

Cool, well I guess I'll just stick with the black one and watch for leaks. So far so good. I thought abot that, so I asked the tech about a possibility that the synthetic may break it down and he said if anything the synthetic should be less corrosive than regular.

I changed to the Syn oil a couple years and 40k+ miles ago. No leaks and no fuss. got Black here. Need one? I dunno, not till it leaks I guess

Tell your Parts Guy to read the TSB's.
I believe mine cost around $16.

http://dieselplace.com/forum/showthread.php?t=22495

FWIW, I left my black one on for a few months after I switched to synthetic, and when I finally got around to changing it, the O-ring looked pretty nasty. It wasn't leaking yet, but would have been sooner or later I imagine.

FWIW, I left my black one on for a few months after I switched to synthetic, and when I finally got around to changing it, the O-ring looked pretty nasty. It wasn't leaking yet, but would have been sooner or later I imagine.

____________

Isn't it fairly simple to change out the O-ring to Nitrile?

mudbug

Ditto Mitch. There is nothing in synthetic oil that will eat "O" rings. Later! Frank

The oring will look like a rubber band that's been in the sun for a month. All crumbly and cracked.

Change your o-ring to one of Nitrile or Buna N composition and it's a done deal. Or, spend the 26$, your call. This ain't rocket science. :)

mudbug

I believe the only reason for white vs black is to ID the compatibility. Whether it was synthetic oil or whatever, mine was severely eaten...

I changed to synthetic on my 02 recently. How involved is the vent replacement? Is it just a straight forward remove/replace or do parts have to come out to do it?

There is a hex nut in the middle. It would be a snap to swap, but I just couldn't understand why it was incompatible with synthetic fluid. I think I'll just wait to see if it starts leaking before I shell out the $25, or look for an o-ring big enough. Do the dealers have just the o-ring?

There is a hex nut in the middle. It would be a snap to swap, but I just couldn't understand why it was incompatible with synthetic fluid. I think I'll just wait to see if it starts leaking before I shell out the $25, or look for an o-ring big enough. Do the dealers have just the o-ring?

Napa has the nitrile/buna-N o-rings as does any hose or hydraulic parts store. Your talking pennies for these.

mudbug

ok question does my 2005 3500 have white or black????

White.

White.

My 2002 I'm sure has the black vent cap, but nothing has been leaking, do I have to re-install the front diff fluid when changing this vent cap, or can I just change the vent cap only?? Thanks!

I have a new extra white cap if anyone in the SoCal Orange County / Riverside County area wants it. PM me.

My 2002 I'm sure has the black vent cap, but nothing has been leaking, do I have to re-install the front diff fluid when changing this vent cap, or can I just change the vent cap only?? Thanks!

Nope. Just take the vent line off, unscrew the old cap and screw in the new cap.

I agree a new o-ring would probably be just as good of fix as the new vent cap. When I bought my cap, I thought maybe there was a difference beyond the o-ring, but I doubt that is the case. I figure for less than 30 bucks it wasn't like it would bankrupt me to get the whole cap anyway.

I have a new extra white cap if anyone in the SoCal Orange County / Riverside County area wants it. PM me.
You can send it to me.

I heard the same thing about the black one leaking with synthetic, so I switched. The parts guys looked at me funny too.

Here's a pic of the difference. The white one has a metal vent too.
http://mysite.verizon.net/vze7z5f3/sitebuildercontent/sitebuilderpictures/frontdiffcover2.jpgWhen I was changing mine out , I noticed the vent is metal on the white and plastic on the black. Seems like the metal one , being heavier would be more likely to stay pointing downward. But I did have a similar experience with the parts people. They had no idea what I was talking about.

:thumb: :hail: Thanks guy's, apprecite the info!!!