Lounge access at IAD?

I'm flying UC to IAD on Monday, then have an onward flight to DFW via ATL in F on DL. I know that I'll be able to use the Skyclub lounge at ATL, but my understanding is DL shares lounges with VS and AF at IAD. Does this mean I'll be able to use the VS lounge, or is the agreement for only proper Skyclubs?

Any advice would be appreciated.

Don't know for sure but as a VS Au who's flown on a VS long haul flight the same day, you're entitled to lounge access when flying DL F in which case you should be allowed access to any lounge DL uses at IAD. In theory at least.