Not to my knowledge it doesn't. Most people don't even know its there, let alone what its actually for. I've never heard of problems with synthetic oil and the diff vent hose.
Look at it this way. The purpose of the diff breather is to equalize pressure between inside and outside of the differential. To avoid pressure building up inside and blowing oil past the seals. The purpose of the hose is to extend where the diff "breaths" to a higher point above the fitting that has been threaded into the top of the diff. Should your hose "come off" or "disintegrate" because of age or hell even the slight chance that synthetic will eat away at it(doubt it), the diff can still breathe.
Basically, even if the hose falls off, or gets eaten up by synthetic, the only time it will become a threat is if your going offroading or crossing through water that will be higher than the top of the diff. Plus, the hose really only see's vapors and fresh air, it never come in direct contact with the oil churning around. Maybe a splash here and there from everything moving around inside but that's about it. If your hose is full of oil, thats a whole nother problem :rofl:
