The last time oil plunged below $50 a barrel, Warren Buffett issued a mea culpa. He had purchased billions of dollars of ConocoPhillips stock near its peak in 2008 and then watched the energy producer’s shares tumble along with crude prices as the recession deepened.

“I still believe the odds are good that oil sells far higher in the future than the current $40-$50 price,” he wrote in a February 2009 letter to shareholders of his Berkshire Hathaway Inc. “But so far I have been dead wrong.”

Oil is back at those low levels after falling from more than $100 a barrel in July. At the very least, that will let the billionaire shave a few dollars at the pump. Last year, he bought a Cadillac XTS -- 18 miles per gallon in the city.

Here are some of the ways that lower crude prices could help and hurt his Omaha, Nebraska-based company this time around:

1. Berkshire is one of the biggest shareholders in Wal-Mart Stores Inc. and also holds a stake in Costco Wholesale Corp., both of which are trading near all-time highs. Lower gasoline prices could boost consumer spending this year, benefiting retailers.

2. Berkshire agreed in October to buy Van Tuyl Group, the largest privately owned network of auto dealerships in the U.S. Cheaper gas has helped increase auto sales and could benefit one of the newest additions to Buffett’s empire.

3. Both jet-fuel and diesel prices have been falling, potentially reducing costs for Berkshire’s luxury aviation unit, NetJets, and its trucking company, McLane.

4. Falling prices at the pump tend to spur people to drive more. That can increase the frequency of accidents and boost costs for car insurers. Berkshire’s Geico is the second-largest seller of auto coverage in the U.S.

5. Surging U.S. oil production has been a boon to Berkshire’s largest subsidiary, BNSF Railway Co. The company has seen an increase in oil carloads from North Dakota’s Bakken region and spent heavily to accommodate them. Some of that demand could go away if oil prices stay low for a prolonged period.

6. Buffett loaded up on Exxon Mobil Corp. in 2013, paying $3.74 billion for about 1 percent of the energy company. While the shares initially climbed after his stake was disclosed, they’ve since fallen back near the price at which he bought them.

7. Buffett’s back-up stock pickers probably underperformed the Standard & Poor’s 500 Index in 2014 partly because of their bets on energy companies. Both Suncor Energy Inc. and National Oilwell Varco Inc. have continued their slide in 2015. Suncor said yesterday that it was cutting jobs and lowering its capital budget to weather collapsing oil prices.

8. Berkshire’s Lubrizol boosted its capacity to make chemicals for the oil industry in December by agreeing to buy two units from Weatherford International Plc. Lubrizol CEO James Hambrick said in December that he wasn’t worried about the short-term effects of declining oil prices on those businesses and expects demand to go up over time.