my dealer replaced the front diff oil to synthetic about 2 years ago and did not change the vent cap to a white one. my question is what harm did it do or not do by leaving the original black cap in ?

Seems like no one really knows what difference the white vent cap makes. When I switched to synthetic, I decided to do what was recommended and change to the white cap. Well the parts counter was confused when I told them what I needed. I gave them the parts number and they said it had changed but they did find me a cap. When I tried to put it in, the taper of cap was slightly different from the black cap and I got it cross threaded. ( I believe the threads were correct, its just that in an awkward position, it was harder to get started. After fighting 45 minutes or so , I checked with the dealer and they assured me that it should be the right part. Anyways, I decided I wasn't going to give them another $25-30 , so I looked at the white versus the black and the main difference (other than color) was that on the white cap, there is a little metal baffle/flipper/thingamajig. And on the black one it is plastic. I don't know what difference that it makes other than the metal being heavier, may keep it flipped in the down position better.

Some on this forum believe that the main difference between the two is the type of rubber seals, and one not being compatible with the other .

Two make a long story short , I really don't know .:rolleyes: Unless your fluid level is low , I would bet that you didn't do any damage.

If it dont leak, dont worry.

The biggest thing according to GM is the seal and its compatibility with synthetic lube.

I ran synthetic about 3 months with the black cap before switching to the white cap. I know many have said the black one doesn't leak, and mine didn't either, but when I took it out the o-ring on it was definitely detiorated. It may never have caused a problem as I can't imagine there is much impetus for oil to pass that seal. Maybe the o-ring was just junk from the beginning and even the dino oil was degrading it? For no more than the white cap cost I'm glad I went ahead and changed it.

The link below says “If the vent hose connector is black in color, it will need to be changed so that the O-ring seal is compatible with the synthetic lubricant. Install vent connector, P/N 12479390 “.

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

Can't remember for sure , but I think I pulled the o-ring from the white cap and used it on the black one when i re-installed it. :o:

At least I hope I did:eek:

http://mysite.verizon.net/vze7z5f3/sitebuildercontent/sitebuilderpictures/frontdiffcover2.jpg

Not a great pic, but shows the difference. I changed mine because I heard the same thing about the gasket. A little awkward to get to, but still pretty easy.