The rumblings about a possible double-dip recession have begun. Investors are understandably worried about such a possibility, not only because it may happen, but because it would be unprecedented for the current generation of market participants.

First, don’t panic. We aren’t there yet. What you can do, however, is start to examine your portfolio for positions that are the most vulnerable and begin adding stocks that will be recession-proof.

In my view, one sector of the market is not only good to hold during a recession, but is in fact bulletproof during the long haul. Its product is not only needed, but required, by businesses and average folks all over the world, every day of every week. Demand for this product rises and falls within a very tight range, but the simple truth is that the world will always need it, no matter what shape the economy is in. Furthermore, it is a tangible and sustainable asset.

I’m talking about oil.

In this case, I’m talking specifically about Chevron (NYSE: CVX). I wrote in a previous article that if I had to choose one oil producer right now, it would be Chevron.

[Read: The Best Stocks to Hold Forever]

What sets it apart from the others?

First, I’m taking BP (NYSE: BP) out of the equation. There’s too much uncertainty surrounding its liability exposure right now to get involved.

Second, I stay away from oil stocks that aren’t based in the United States, Canada, Britain or Australia. There’s too much potential instability in the non-Western producers.

Now, let’s take a look at some numbers, which will help articulate my perspective.

The first thing I always look at with companies, like oil producers, that are really all about cash flow — is relative valuation. It is generally the deciding factor right out of the gate. I tend to forego the P/E and PEG ratios because their utility decreases with slow-growth companies like these.

So I use EV/EBITDA instead, which looks at the size of the company in relation to how much cash flow it generates. What we see is that Chevron and Conoco Phillips (NYSE: COP) are almost one third cheaper than Exxon and Occidental Petroleum (NYSE: OXY) based on this metric. This is true despite Exxon whipping up $40 billion in free cash flow (FCF) in 2008, due to superior expense control.

Next I look at past and future growth. Chevron is second in market cap to Exxon, so I am pleased to see it has been growing three times faster. Going forward, the growth rates bunch closer together, but +2% growth between Chevron and Exxon Mobil is a lot when you are talking about companies that generate tens of billions of dollars in net income each year. Chevron wins this category, with Exxon coming in second, and Occidental Petroleum out of contention at this point.

From here, I look at cash and debt. As all these companies literally throw off billions in free cash flow each year, solvency is not an issue, so debt and debt service as a whole is of little concern.

#-ad_banner-#I’m more interested in which has excess cash, as it allows for flexibility for expansion, new technology and (God forbid) remediation should a disaster strike. So, in a pinch, which do I want to hold? Conoco is done at this point, because it is much further in debt than the others. It’s not a big deal, but I don’t want to be holding the stock if some disaster should befall. Chevron wins the faceoff here with a net cash position.

Dividends are nice to have, especially for a “Forever Hold” type of stock. Reinvested dividends really turbo-charge returns during 30 years or so, so Chevron wins again.

Action to Take–> Buy Chevron. The world will always need oil, no matter what shape the economy is in, regardless of what oil prices do. The company has a rock solid balance sheet with billions in profit and free cash flow and a yield approaching 4.0%.

As the second-largest oil producer by market cap, the company still has plenty of market share to take away rather than to lose. Most of all, in the event of a double-dip recession or even a depression, financial assets will get destroyed, so you’ll want to double up on a stock like Chevron for its tangible, non-financial asset of black gold.