US crude oil inventories rose by 6.8 million barrels in the week that ended Friday, the Energy Information Administration said.
For the second consecutive week, the build up more than expected. It was also the the third consecutive week of increases with stockpiles adding a total of 14.9 million barrels in that time.
Crude oil stockpiles have spent only two weeks this year -- the last two weeks of September -- below the agency's seasonally adjusted upper range.
EIA said supplies of motor grade gasoline rose by 100,000 barrels to 219.9 million barrels and are at the top of the average range for this time of year.
Supplies of distillate fuels, which include home heating oil, fell by 3.1 million barrels to 126 million and remain near the lower limit of the average range for this time of year.
The national average retail price of regular unleaded gasoline fell for the fifth consecutive week.
The national average price dropped 5.8 cents to $3.367 per gallon. The price is 48.3 cents per gallon below the price in the same week of 2012, the EIA said.