Blue-Chip Stocks Recover, Oil Retreats  NEW YORK (Reuters) - U.S. blue-chip stocks changed course  and rose late Tuesday afternoon as a drop in oil prices helped  steady the market, although investors remained cautious before  tech bellwether Intel Corp.'s &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=INTC.O target=/stocks/quickinfo/fullquote"&gt;INTC.O&lt;/A&gt; earnings.