Shares of oil giant ExxonMobil (XOM -3.01%) broke a two-day losing streak on Friday, turning around and moving higher to follow oil prices that are rising in response to positive OPEC news out of Goldman Sachs.

As of 2:30 p.m. ET Friday afternoon, Exxon stock is up 2.6%.

ExxonMobil stock tracks oil prices

After last bottoming out in late June below $68 a barrel, the price of WTI crude oil went on a wild ride that ended well above $90 in late September -- only to turn tail and plunge thereafter. Through Thursday's close, crude oil prices had plumbed lows last seen in early July and seemed destined to return to June levels -- until today.

Today, both WTI and Brent (the international benchmark) crude oil prices are bouncing about 4% higher, up past $75 and $80 a barrel, respectively, and ExxonMobil stock and other oil stocks are reacting positively to the news.

The rebound follows positive commentary from Goldman Sachs analysts, who point out that "$75 oil has previously sparked a response from OPEC," which is planning to meet to discuss oil production quotas next weekend. Goldman thinks OPEC -- and Saudi Arabia in particular -- are likely to tweak production rates to ensure oil prices rise to at least $80 next year, and probably maintain a price range between $80 and $100 a barrel.

What $80 oil means to Exxon

It may be that $80 oil is a kind of sweet spot for ExxonMobil. Reviewing price charts on Oilprice.com, it appears oil traded more or less steadily around $80 a barrel in this year's Q1, for example. Not coincidentally, Q1 was Exxon's best profit-making quarter so far this year -- even better than last quarter, when oil prices briefly surpassed $90.

Exxon earned some $11.4 billion in profit in Q1 this year, according to data from S&P Global Market Intelligence, versus $7.9 billion as oil prices dipped in Q2 -- but also versus $9.1 billion as prices turned more volatile, both rising and falling, in Q3.

If next year is going to look a lot like Q1 this year, therefore, that would bode well for Exxon stock. And seeing as Exxon shares cost less than 10 times earnings today -- while paying a generous 3.7% dividend yield -- this suggests that now might be a good time to invest in some ExxonMobil stock.