Think all large-cap oil stocks are the same? Think again.

Exxon Mobil (NYSE:XOM) might look like BP (NYSE:BP), Chevron (NYSE:CVX) and ConocoPhillips (NYSE:COP) on the surface. When you look under the hood, though, there’s something different about Exxon Mobil that might motivate you to steer clear.

Birds of a Feather Not Flocking Together

First and foremost, investor returns have been oddly varied from one of these stocks to the next. During the past three years — the span of the economic recovery — ConocoPhillips shares have advanced a little more than 100%, while Chevron is up 70%. Yet Exxon Mobil shares have gained just 23%. That’s only a tad better than the performance of BP — you know, the $136 billion company that created more than a $20 billion liability for itself by spilling nearly 5 million gallons of crude oil into the Gulf of Mexico in early 2010?

Think about that for a second. Exxon Mobil, which didn’t create the worst environmental disaster in more than a decade, has rewarded investors almost as poorly as the company that did.

At the heart of the stock’s stagnation is tepid earnings growth. Though Exxon Mobil’s bottom line of $41.0 billion last year is better than 2009’s $19.3 billion, it’s still shy of 2008’s net income of $45.2 billion … the only one of the four major oil names in focus to do worse last year than it did in 2008.

And here’s the amazing (again, not in a good way) part about Exxon’s returns over the past three years: The company was buying back a truckload of shares during that time, which should have significantly helped the stock’s value and earnings. It didn’t. Although XOM has bought back $52 billion worth of its own stock since 2009 — about 13% of the current $395 billion market cap — last year’s per-share profit of $8.42 still is weaker than 2008’s $8.66.

It all begs the question: Why can’t Exxon do what the other major players seem to be able to do?

The Hard Part About Hating It

Performance numbers aside, the company seems to be an attractive one. Exxon Mobil invests a great deal of money back into its business. Indeed, it has budgeted $185 billion for exploration and development over the next five years. That’s huge — huge enough to increase the company’s output by an estimated 1 million barrels of crude per day. The raised output will translate into a little more than $36 billion in additional annual revenue at today’s oil prices.

Of course, it won’t benefit XOM shareholders anytime soon, since every bit of that new incremental revenue for the next five years is being laid out to turn those revenue spigots on. Yes, after that period Exxon will benefit from greater production, if those new sources last for more than five years — a serious concern in the shadow of weakening production forecasts for 2012.

Unfortunately for current shareholders, the only thing that really matters in terms of a stock’s price are the “here and now” performance numbers. And Exxon Mobil just doesn’t look poised to post any strong ones for a while.

Plus, there’s no guarantee XOM won’t have to keep pouring a ton of cash into new development beyond the current five-year plan. After all, its current oil and gas sources are already starting to dry up, hence the lowered output expectation for this year.

Bottom Line

None of this is to say Exxon Mobil is a bad company. It’s a fine company, particularly if you like dividends and take comfort in size. The yield of 2.2% is respectable, and grows reliably, and the company’s $395 billion market cap makes it one of the biggest in the world.

It seems, however, that size also has made it tough for Exxon to grow the top and bottom lines. Where else can it go to win new customers as well as efficiently develop new production? The answer: not enough places.

So, while it’s hard to say it’s an outright “sell,” Exxon Mobil is the last major integrated oil name that should be considered a “buy.” Energy investors might want to explore other options — even BP, now that the fallout from the Gulf of Mexico oil spill is starting to settle.

As of this writing, James Brumley did not hold a position in any of the aforementioned securities.