* Woodside Petroleum drags energy stocks lower

* Westpac hits one-year high

* CSL has best day in two months

Feb 18 (Reuters) - Australian shares ended a volatile session flat, with lacklustre annual results from Woodside Petroleum dragging energy stocks lower, while Treasury Wine notched its best day in five years after the company unveiled plans to overhaul its business.

The S&P/ASX 200 index ended flat at 6,885.9 points on Thursday. The benchmark closed 0.5% lower on Wednesday.

"It (the market) is directionless right now," said Brad Smoling, managing director at Smoling Stockbroking.

"We don't have any sort of negative or positive lead to follow and no one wants to take a position in a big way until we see some sort of marcoeconomic change, or have a disaster in reporting, which we haven't had yet."

Energy stocks shed 1.5%, with Woodside slumping 2.4% after its annual profit more than halved.

Shares of fuel supplier Viva Energy fell 2.5% and power company Origin Energy dropped 2.2% after its first-half profit was nearly wiped out.

Treasury Wine Estates, which extended gains to a second session, climbed 17.5% to mark its best day in more than five years after the world's largest listed winemaker said on Wednesday that it would reorganise into three internal divisions and likely sell low-priority brands and other assets.

Healthcare stocks hit their highest in nearly two months, helped by sector heavyweight CSL, which advanced 2.8% after a jump in half-year profit.

Financials gained 0.3%, as Australia and New Zealand Banking Group reported a higher first-quarter profit and said it was well-positioned for the rest of the year.

Peer Westpac gained 3.5% to hit its highest in nearly a year.

Miners closed 0.2% weaker, with BHP Ltd ending in negative territory.

New Zealand's benchmark S&P/NZX 50 index closed 0.32% lower to finish at 12,633.6 points.

Six of the nine major sectors on the bourse closed in the red, with Air New Zealand being the top loser in the index. (Reporting by Harish Sridharan in Bengaluru, Editing by Sherry Jacob-Phillips)