If you are searching out big dividend yields in the energy patch, then you'll want to examine Sunoco LP's (SUN -3.10%) 7.6% yield and Magellan Midstream's (MMP) even higher 8.6%. But be leery of Devon Energy's (DVN -0.83%) 9% yield. There are very big differences between the business model of Sunoco and Magellan and that of Devon Energy that make the former two reliable payers and turn Devon into a high-risk dividend play.

Magellan Midstream: A long distribution history

Magellan Midstream is a master limited partnership (MLP) focused on the midstream space, as its name implies. It is keenly centered on collecting fees for moving oil and refined products, like gasoline and diesel. In this way, it is a play on the old gasoline-powered engine, which is being replaced by electric vehicles (EVs). This is one of the reasons the MLP's distribution yield is so high.

That said, gasoline remains a vital energy source in the world despite the headline-grabbing shift toward electric vehicles. In fact, EVs only make up a mid-single-digit percentage of the U.S. vehicle fleet.

If you can think in a contrarian manner, Magellan should remain a vital part of the auto ecosystem for years to come. But because its business is fee-based, the prices of oil and gasoline shouldn't create much volatility for it.

However, there's another small wrinkle to monitor. The MLP's distributable cash flow covers its distribution by around 1.2 times, which used to be considered strong in the midstream sector but today is toward the lower end of the spectrum.

Magellan has increased its distribution annually since its initial public offering in 2001. It also has an investment-grade-rated balance sheet. So there's a material reason to believe the company can continue to support the payment, though you'll want to monitor its distribution coverage just the same.

Sunoco LP: The gas station supplier

Staying with the gas-engine theme, yield seekers who can think outside the box will also like Sunoco LP. This partnership's role in the energy sector is moving energy, and its business is supplying gas stations with fuel. It has been moving to expand beyond this to include pipelines and storage, but fuel distribution is still the business to watch. And it has been a very good one.

For example, Sunoco covered its third-quarter 2022 distribution by a generous 1.8 times. That provides ample room for adversity before the MLP's distribution would be at risk of a cut. Unlike Magellan, Sunoco doesn't have an investment-grade-rated balance sheet (it's just shy of that mark), so it probably needs to have extra breathing room on the distribution just in case. However, it is worth noting that Sunoco went a decade without a distribution cut despite extreme volatility in the energy sector.

The hefty coverage, meanwhile, also hints that the company could continue to use its extra cash flow for accretive acquisitions. This has been and will likely remain a key growth driver.

Devon Energy: Volatility that's built in

The last name up is Devon Energy. It is not a bad company, and nothing here is meant to suggest such a thing. The problem for dividend investors is that you simply can't rely on the dividend. That's by design, since the company's payout is variable, with a core dividend and a supplemental payment that fluctuates based on the company's financial results. And since Devon is an oil driller, its performance is going to track along with often-volatile energy prices.

The 2022 third-quarter dividend is a great example. The payment was $1.35 per share, which the company happily announced was 61% higher than the same quarter of 2021. What management didn't mention was that this was down from $1.55 in the second quarter of 2022, a roughly 13% decline. The big takeaway is that the high yield here simply won't last, because history has shown that high oil prices just don't stick around forever.

Be careful what you buy

There's no question that Magellan and Sunoco LP come with risks, the most notable being the long-term shift away from gasoline-powered vehicles. However, that transition is likely to be decades in the making, which should allow the MLPs to support their big yields for many years to come.

Devon Energy's dividend, meanwhile, is built to change just as quickly as oil prices do, which is a good reason for investors who are looking to create a reliable dividend stream to avoid it.