Despite recurring rumors of peace feelers, the 4 1/2-year-old Persian Gulf conflict shows no sign of ending largely because neither Iraq nor Iran can stop the other from exporting oil to pay for it.

That remains the sobering lesson of the year-old "tanker war" that Baghdad launched with high hopes of forcing Iran to the negotiating table. A frustrated Iraq now tries to reach that goal by stepping up air raids against civilian targets, and Iran replies in kind.

A year ago, Iraq's French-built Super Etendard fighter-bombers -- later joined by more modern F1s -- began firing Exocet missiles at shipping within a 50-mile exclusion zone around the main Iranian oil facility at Kharg Island.

Beginning last April, then increasingly in May, the tanker attacks raised the specter of internationalizing the conflict. It was suggested that the superpowers would intervene to stop the war rather than risk having the fighting spread.

Pessimists predicted yet another steep rise in oil prices. But market forces, human ingenuity and a surprising accommodation to danger combined to thwart Iraqi plans.

"It's hard to believe that millions of dollars worth of investment and the lives of seamen aboard tankers and other ships plying the gulf are at risk," a western diplomat remarked, "but frankly, it's become a bore, a case of another day, another ship attacked. No one seems to care."

In a period of prolonged oil glut, Iran discovered that owners of laid-up tankers were prepared to risk sailing to and from Kharg Island for a price.

Weeks went by without any Iraqi attacks, which, in any case, proved less effective than originally thought. Iran replied in kind to about half the Iraqi attacks.

But crude oil has a high flash point and does not ignite easily. In addition, Iraqi pilots were often poorly motivated and did not press home their attacks. Ecologists, who had feared massive damage from crude oil released from sunken tankers, began to relax. So far only one tanker has been sunk and it was transporting refined products, which evaporate more easily than crude.

But with soaring insurance rates and salary premiums payable for every day spent in the gulf, Iran was forced to grant big discounts to owners risking the Kharg Island run. That trade continues.

By November, Iran also had started operating an oil shuttle with chartered medium-sized tankers -- hardly worth expending an Exocet on -- between Kharg and Sirri Island. Sirri is inside the Persian Gulf but much closer to the Strait of Hormuz and the mouth of the gulf and well within air cover from the Iranian air base at Bandar Abbas.

Two giant tankers anchored at an old oil terminal at Sirri act as storage reservoirs. Customers send their own supertankers there to load crude at a smaller discount reflecting reduced time spent in the war zone and thus reduced insurance.

Iran is earning between $10 billion and $15 billion annually from oil, according to specialists. The wide variation reflects the specialists' difficulty in evaluating the importance of spot sales and complicated barter deals.

Some specialists wonder why Iran has not yet expanded its exports by building a pipeline to Bandar Abbas or another port outside the gulf, although construction costs would be high because of rugged, mountainous terrain.

Iraq had little choice but to build new pipelines. Although Iraq has said it invaded Iran in 1980 in order to regain control of the Shatt al Arab waterway, one of Iraq's goals is believed to have been capture of Iran's oilfields. Iraq failed, and Iran in turn destroyed Iraq's terminal facilities at Fao on the gulf in the early days of the fighting.

Iraq has increased the capacity of its pipeline through Turkey to the Mediterranean to 900,000 barrels a day and is reportedly considering a decision to go ahead with a second 700,000 barrels-a-day pipeline.

Iraq's present annual oil revenues are estimated at $9.5 billion. In addition to the oil exported by the pipeline, 100,000 barrels a day of refined products are trucked to Turkey and to the Jordanian port of Aqaba, with access to the Red Sea.

Additionally, just under $2 billion is earmarked for Iraq by Kuwait and Saudi Arabia from oil sales from the former neutral zone at the border between the two countries.

By next September a $500 million, 400-mile spur pipeline will increase Iraqi exports by 600,000 barrels a day by linking northern Iraqi oilfields with a Saudi pipeline ending at Yanbu on the Red Sea.