About 600 tanker drivers are expected to strike
Downing Street has urged motorists not to panic-buy petrol and diesel ahead of a planned strike by tanker drivers delivering fuel for Shell on Friday.
A spokesperson for Prime Minister Gordon Brown said contingency plans were in place to minimise disruption.
Even so, the government said that some petrol stations could run out of fuel.
Hundreds of members of the Unite Union are due to walk out from 0600 BST on Friday until 0600 the following Tuesday in a dispute over pay.
The drivers work for Hoyer UK and Suckling Transport, haulage firms employed by Shell to deliver fuel to its forecourts across the UK.
The prime minister's spokesperson said: "We believe that this strike is unnecessary and we would want to ensure that nothing was done that inconvenienced the public.
"But the most responsible thing the public can do is to continue to buy as normal."
The Department for Business, Enterprise and Regulatory Reform (BERR) estimated that Shell accounted for about one in 10 filling stations in the UK and that it was "inevitable" some of them would run out of fuel.
Shell is understood to have a dedicated team working to minimise any disruption by maximising stocks of fuel and prioritising deliveries.
A series of measures was enacted by the government last Friday to allow companies to work together in order to get fuel to where its needed in the event of a strike, while remaining within the scope of competition law, BERR said.
However, the Petrol Retailers Association, suggests that the impact of the four-day strike may not be as great as some fear.
"One forecourt in ten might not have sufficient fuel for the period of the strike," the association's Ray Holloway told the BBC.
"But on the plus side, any forecourt would normally hold four days' stock, so the effect could be an awful lot less than some people may project," he said.
In an attempt to resolve the dispute, representatives from the Unite union are due to meet the two transport firms on Wednesday.
The union claims that drivers' average pay before overtime of £32,000 has not increased since 1992. It suggests a wage of £36,000 a year would be fairer.
Drivers have rejected an improved offer of a 6.8% pay rise, which the companies claim would have increased drivers' average salaries, including overtime, from £36,500 to around £39,000 a year.
Hoyer UK estimates that that if drivers had accepted that latest offer, their average pay would have increased by a third over the past five years.
The talks due to begin on Wednesday will involve the arbitration and conciliation service, Acas, for the first time.
"I hope that by involving Acas we can avoid industrial action," said Bernie Holloway from Hoyer UK.
The Unite union renewed its insistence that Shell should intervene to resolve the dispute.
"Only Shell sets the terms of this contract and only it can solve this dispute," said Len McCluskey, Unite's assistant general secretary.
"This is one of the most profitable companies on earth and it now needs to provide the financial flexibility to avert this dispute," he said.
In a statement, Shell said it "urged both parties to find a way through their differences".