Want to give you portfolio a big advantage? Buy what Warren Buffett is buying. His portfolio has beaten the market for decades, and choosing from stocks he's already purchased instantly gives your portfolio a leg up on the competition.

Right now, two Buffett stocks in particular look too cheap to ignore. The first is a great option for oil bulls. But the second is a great pick no matter what your investing style is.

Bullish on oil? Check out this stock.

Oil prices have been on a roller-coaster ride in recent years. In 2020, they fell below $25 per barrel. But two years later, they peaked above $125 per barrel. Right now, they're back around $70 per barrel. If you think prices are set to rise again -- whether that's due to emerging market demand or geopolitical uncertainty -- there's one stock you need to take a closer look at: Occidental Petroleum (NYSE: OXY).

Buffett has been invested in Occidental for several years. But he's been consistently buying over time, gradually increasing his stake to enormous levels. Last quarter, he bought more than 7 million shares at his holding company, Berkshire Hathaway, bringing the position value up to $16 billion.

What does Buffett like most about Occidental? It could be its leverage to rising oil prices. As an oil company primarily exposed to upstream operations, Occidental is particularly exposed to changes in oil prices. And following its $12 billion acquisition of shale producer CrownRock, the company could see its value soar if oil prices rebound higher.

According to Occidental's management team, cash flow would rise by around $260 million for every $1 uptick in oil prices. At peak 2022 levels, that could result in enough additional cash flow to finance the entire CrownRock acquisition. Of course, oil prices are roughly $50 per barrel lower than they were in 2022. But as history has proven, a lot can change in two years. If you believe in rising oil prices, Occidental is a great pick. Just know that the upside potential is equally matched by downside potential should oil prices weaken further.

This Buffett stock is a growth superstar

You don't have to be bullish on oil prices to love Nu Holdings (NYSE: NU). Buffett got in early on this little-known growth stock, but he has yet to sell a single share of his $1.4 billion position.

What does Nu do? If you lived in Brazil, Mexico, or Colombia, you'd probably already know the answer. The fintech company operates exclusively in those markets, delivering a suite of financial services -- everything from credit and debit cards to crypto trading and personal insurance -- digitally. This business model was clearly in demand. Over the last decade of operation, Nu has gone essentially from zero customers to more than 100 million.