But disappointingly operating earnings and cash flow from operations declined year-over-year by 25% and 4% respectively. The decline can be attributed to an 8% year-over-year decline in oil production for the quarter to an average of 500,000 barrels of oil per day. This was caused by a combination of planned maintenance outages as well as a number of unexpected outages. These included labor disputes in Libya, the indefinite suspension of its Syrian operations and flooding in Alberta.However, Suncor Energy Inc. (USA) (NYSE:SU)' results for the remainder of 2013 and into 2014 should improve considerably. Primarily, because of higher crude prices combined with increased production on the back of the completion of the planned maintenance at Upgrader 1, the Edmonton refinery and Firebag . Improvements to hot bitumen transport and storage infrastructure at Firebag and Suncor's Athabasca terminal, have also unlocked constrained capacity . All of which increases operational flexibility, allowing Suncor to optimize its sales mix. Suncor appears particularly cheap, trading with an enterprise-value of five times its EBITDA and fourteen times it's proved oil reserves. Another compelling aspect is that Warren Buffett-who is considered to be the world's greatest investor-has taken a bullish view on Suncor Energy Inc. (USA) (NYSE:SU)'s prospects. By the end of June 2013, Buffett's Berkshire Hathaway Inc. (NYSE:BRK.A) had amassed almost 18 million shares or just over 1% of Suncor, valued at approximately $500 million. This makes Berkshire Hathaway the 16th largest share holder in the company. Exxon Mobil makes further unconventional acquisitions in Canada The 'king of oil' Exxon Mobil Corporation (NYSE:XOM) continues to expand its interest in Canadian oil sands. It recently acquired ConocoPhillips (NYSE:COP) interest in an oil sands project in Alberta Canada. This acquisition boosted Exxon's already significant Canadian presence, through its 70% controlled Canadian subsidiary Imperial Oil Limited (USA) (NYSEAMEX:IMO). The deal has seen Exxon Mobil Corporation (NYSE:XOM) acquire 226,000 acres of undeveloped land, roughly 93 miles south of Fort McMurray, Alberta for around $720 million. The land is known as the Clyden oil sands leasehold. When the deal closes, Exxon will own a 72% interest in the land and Imperial Oil Limited (USA) (NYSEAMEX:IMO) will control the rest. Already Exxon Mobil Corporation (NYSE:XOM) has invested $11 billion in unconventional oil sands development and production in Canada and this acquisition will boost its proved oil reserves and eventually production. Like Suncor Energy Inc. (USA) (NYSE:SU), Exxon also reported some disappointing second quarter 2013 results. Exxon Mobil Corporation (NYSE:XOM)'s bottom line plunged by 19% year-over-year on the back of softer prices for crude and refined products, excluding a large one time item. This has seen Exxon's share price decline leaving it trading just above it 52 week low of $84.70. As a result Exxon is now trading with an enterprise-value of six times EBITDA and 16 times its proved reserves, making it appear cheap but not as cheap as Suncor Energy Inc. (USA) (NYSE:SU). Imperial Oil Limited (USA) (NYSEAMEX:IMO), Exxon Mobil Corporation (NYSE:XOM)'s Canadian subsidiary continues to perform strongly, but like its peers its second quarter financial results declined significantly because of softer crude prices. Imperial Oil's bottom line plunged by almost 50% year-over-year to $310 million, despite revenue growing by 6% year-over-year for the same period.