Don't do it. I needed to re-login into my eBay account last week and it asked me to use my google account to log in, didn't think much of it, because that's how I log into FB and other accounts and went ahead. The next day I logged in again because I had sold an item and my account was gone, I had logged into an account with a similar users name, but no activity whatsoever. Nothing got compromised fortunately.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).