As oil traders have learned time and again, picking a bottom in today’s glutted global market can be a fool’s game: just when prices start to rebound, as they have three times this year, a wave of renewed bearishness smacks them back down.With oil resuming its southward march due to yet more oversupply, closing in on $35 a barrel after trading at $100 in June 2014, any number of factors could indicate when the rout may finally be over — for real this time.PUMP THAT SHALE OR NOTThe United States is still pumping near-record volumes of crude, while OPEC is keeping output near all-time highs to maintain market share. But the strain is starting to show. US oil production has fallen by about 200,000 barrels per day since an over four-decade high in April, a decline that’s been far shallower than many expected. Non-OPEC annual supply growth shrank to below 300,000 bpd in November from 2.2 million at the start of the year, according to the International Energy Agency. New data showing a deeper or more definitive decline in output could give bulls a reason to pile back in.WELL, WELL, WELL: YOU DON’T SPEND, YOU DON’T GETIf any one thing points to the dangers of a supply shortfall in the future, it’s a lack of investment. As ex-BP chief Tony Hayward told a conference in New York this year, if the money doesn’t go into the ground, the oil won’t come out. Non-OPEC investment has been cut by around $130 billion this year from about $650 billion in 2014, OPEC Secretary General Abdullah al-Badri said in October. In the United States, the oil rig count just keeps falling. Last week it dropped for the 14th of the last 15 weeks, to 524, a third of what it was a year ago. A Barclays survey found that North American oil firms could cut investment by up to $19 billion next year after slashing it by $68 billion this year.SAUDIS BLINK?Led — or dragged — by Saudi Arabia, the Organization of the Petroleum Exporting Countries this month came to a non-agreement that essentially keeps output unchanged. The group’s refusal to cut production — or even simply set a ceiling — has sent prices into another tailspin, but that could change at any time. Riyadh is feeling the strain, albeit less so than poorer OPEC members like Venezuela and Iran. Saudi officials have already floated ideas such as a value added tax and cutting energy subsidies. The Kingdom has resolutely refused to back down on its policy of pumping flat out, but any indication of a softening resolve could mark a true turning point.WAR-WAR, NOT JAW-JAWThese days, the specter of a wider supply-disruptive war is never far off, and when it hits oil-producing regions, skittish traders look to buy. With Iraq and Syria in disarray, Saudi bombing Yemen, and Russia still embroiled in conflict with Ukraine, there is plenty to watch. Compounding the risk, the amount of available spare OPEC oil capacity that could compensate for any sudden shortage has shrunk to just around 1.25 million bpd, the least since 2008, according to the EIA.WAITING FOR IRANOne major factor weighing on oil markets is the expected reemergence of Iran as an exporter next year after sanctions are lifted. Tehran has said it is gearing up to pump an extra 500,000 bpd of crude as soon as mid-year as sanctions are eased within months. If those exports do not materialize or are delayed, bulls may be emboldened to charge in.ZOMBIES SWARMUS oil companies are feeling the strain and many, known as “zombies”, have stopped pumping as they wait out the downturn, saving cash and paying off what debt they can. If oil prices remain low, credit lines may be cut, sending companies under and cutting output capacity. The decision by most banks not to cut credit to producers this fall was bearish but if that leniency does not continue it will have the opposite effect.GET IN THE CARWhen crude drops, so do gasoline and diesel prices, and consumers worldwide are driving more. If that continues, it will be a supportive factor. British supermarket chains Asda and Morrisons have cut the price of petrol to below the 1 pound ($1.50) per liter mark, and others are expected to follow. China’s car sales jumped 20% in November from a year earlier, putting the world’s biggest automobile market on track for annual sales growth of 5 to 7%. And consumers are also showing less interest in more fuel-efficient cars — US vehicle fleet efficiency was flat in 2014 and will barely rise this year, US data show.BALANCE WILL RETURN, GRASSHOPPERFor all the talk of oversupply, it may not be as big as many think. Global markets are only oversupplied by about 1 million bpd, according to a report from Citi analysts on Tuesday, and a bridging of the gap is already under way. With incomplete and often lagging data, any sudden sign that the supply excess is diminishing more quickly than expected could ignite buying.CHARTS DON’T LIE, DO THEY?Traders are mulling price charts which point to the possibility of a further drop in crude. But if supportive levels are not breached there could be a rebound. Technical analysts say if downward momentum runs out at the key support level of $35, prices will likely rebound. Some are looking back to the December 2008 lows as key supports; if US crude avoids sinking below $32.40 a barrel, the bottom could be in. It was trading about $3 a barrel above that on Wednesday.