Cape Town - Petrol is set for a drop of approximately six cents a litre for unleaded 95, and two cents a litre for 93, according to the Automobile Association (AA).
The price reduction for diesel is expected to be two to four cents a litre, with illuminating paraffin down by a cent, the AA said.
The AA was commenting on unaudited month-end data released by the Central Energy Fund (CEF).
"The weakening rand has yet again seen South African motorists miss out on substantial drops in international oil prices.
"Almost 60 cents a litre in price relief has been lost to the rand in the past two months," the AA said.
Fuel prices are set to show only slight declines at month end, as the benefits of the retreating oil price continue to be offset by a weaker rand.
"If the rand had held steady at its early-November levels, we would be expecting fuel prices to drop by 25 to 30 cents a litre thanks to a weaker oil price," the AA said.
"However, the month-end pictures mirrors that seen at mid-month and the decline in the rand/US dollar exchange rate has closely matched oil's gains. We expect only marginal changes in the fuel price."
By late Thursday afternoon the rand was trading at R14.27/$, while oil traded at $45.46 a barrel.
The Department of Energy is due to announce the fuel price adjustments on Friday. Any price changes will then take effect next Wednesday.