AUGUSTA — Mainers who heat their homes with oil should top off their fuel tanks soon and consider installing a second tank, state energy planning officials said as the Persian Gulf crisis continued.

Two weeks ago, consumers were being advised to delay purchases in the hope that oil prices would stabilize.

Oil tank wholesalers recently reported brisk sales and installers said more homeowners are inquiring about getting spare tanks.

Installing second tanks generally costs about $400, according to Ralph Perkins, vice president of Don Rich Heating Co. in North Windham. Dealers who supply tanks are increasing their inventories, said Edward Sterner of Colonial Supply Corp. in Portland.

The mini-run on tanks came as state energy officials warned Mainers not to be caught short if the Mideast crisis causes oil supply problems as the weather turns cooler.

“The cost of getting prepared, if it’s necessary, is relatively insignificant compared to the cost of not being prepared,” said John Flumerfelt, director of energy planning for the state.

The state’s recommendation to install second tanks stems from information gathered last winter, when heating oil prices rose sharply during the December cold snap. Flumerfelt said residents should try to have one-half to two-thirds of their annual oil needs in storage.

The average home uses 800 gallons a year, and the average tank holds 275 gallons. A second tank could pay for itself in a year or so for homeowners who have it installed and filled before the heating season, when prices are still 10 cents to 15 cents a gallon below peak.

Gene Guilford, president of the Maine Oil Dealers Association, agrees that having a second tank installed can provide a hedge against price swings. But he said that topping off tanks now is “ill-advised” because world markets and strategic oil reserves can cover the loss of production in Iraq and Kuwait.

Only a disruption in Saudi Arabian output would drastically affect supplies, said Guilford.

Flumerfelt said there is a “very real possibility that Persian Gulf events might worsen and Saudi production may be threatened.”