Hogan said it will be key to see if oil goes back below $40 a barrel, a level it was last at in April. Energy analysts say it could fall into the mid-$30s or lower.
"$35 is the next target lower. I think if it got down to $35, you'd have people stepping in. The fundamentals are a lot better than they were at the beginning of the year. … I don't think anything with a $20 handle is in the cards," said Mike Dragosits, senior commodity strategist at TD Securities.
Oil is now down more than 21 percent from its June 8 high and has been falling on fears of a glut, not only for crude but for refined products. API inventory data is reported Tuesday afternoon.
Stocks ended mixed Monday, with the Nasdaq up 22 at 5,184 while the Dow was down 27 points at 18,404 and the S&P 500 was down 2 to 2,170. The Nasdaq rose with biotech, but the 3 percent decline in energy shares weighed on the S&P 500.
The Dow was down for a sixth day. "It's just a mild drift lower," said Hogan. "It's not even down a percentage point in six days."
Vehicle sales for July will be reported Tuesday morning and are expected to come in at an annual selling rate of just above 17 million, up from 16.7 million last month. But car sales are seen as peaking, particularly after Ford Motor predicted slower sales in the U.S. for the second half.
"Car sales trends have been good, and that's been an important part of the recovery we've seen over time. We've been talking about the auto peak for three months. It hasn't exactly hit us yet," said Hogan.
Personal income and spending and the PCE price index will be important at 8:30 a.m. EDT. The June report is expected to show a gain of 0.1 percent in the price index, which is the Fed's preferred inflation measure.
Income is expected to rise 0.3 percent, and spending is also expected to be up by 0.3 percent. The June report is important, but traders are awaiting the July jobs report Friday, even more important since the report of very weak second-quarter GDP last week.
Second-quarter GDP grew by just 1.2 percent, less than half the pace expected by economists. That report, released Friday, puts the spotlight on all third-quarter data now, which will be more impactful as investors weigh whether that sluggish growth will be a continuing trend.
"To me the GDP data didn't look that good. It's close to 1 percent for three straight quarters," said Chris Rupkey, chief financial economist at MUFG. "That fits with [Fed Chair Janet] Yellen's idea that rates are going to stay lower for longer."
Rupkey had expected the Fed could hike rates in September, but the GDP reading signaled that it will likely hold off. New York Fed President William Dudley on Monday said it was premature to rule out tighter policy this year, but he also stressed data will be key to rate hikes.
"I think they're struggling to come out and explain why the market has one or two rate hikes, and they have six or seven rate hikes over the next couple of years. They keep hitting back and saying the market is complacent," said Rupkey. "… he kind of talked out of both sides of his mouth."
As for Fed speakers, Dallas Fed President Rob Kaplan speaks in Beijing at 6:15 a.m. EDT.
Tuesday will be a busy day for earnings, with Procter & Gamble, Pfizer, CVS Health, Honda Motor, Aetna, Archer Daniels Midland, Seagate Technology, Cummins, Cardinal Health, Eaton and many others reporting before the bell.
AIG, Electronic Arts, FMC, Tableau Software, Devon Energy, Avis Budget, Tableau Software, Newfield Exploration and La Quinta are among companies reporting after Tuesday's closing bell.
Ahead of U.S. trading, investors will be watching Japanese Prime Minister Shinzo Abe's announcement of details on the latest fiscal stimulus package to boost Japan's economy. His cabinet is expected to approve the plan.