Imported petrol was cheaper than Dangote's price on 1 September, by Legit.ng's tracking. By 8 September a marketers' association put the landing cost above it. Dangote raised its price on 12 September.

Landing cost is an estimate of what it costs to bring petrol into a Nigerian port, built from international product prices, freight, financing, port charges, levies and the exchange rate. The gantry price is what the refinery charges marketers at its loading point. Both sit upstream of the pump price.

Legit.ng reported on 3 September that imported petrol had dropped below Dangote's price. By its tracking, imports cost about ₦1,239 a litre on 1 September, against Dangote's ₦1,265. Legit.ng doesn't say what that figure includes. The same report cautioned that the refinery could raise its price by at least ₦50 if conditions worsened.

The next figures come from a different source and shouldn't be read as a continuous series. The Major Energies Marketers Association of Nigeria put the landing cost at ₦1,311.36 on 8 September. That was ₦46.36 above Dangote's ₦1,265 gantry price and ₦95.02 above the association's own 30-day average. Legit.ng reported the association's figure at ₦1,314.67 on 10 September, against a listed Dangote price of ₦1,265.50.

On 12 September, Dangote raised its gantry price by ₦85, from ₦1,265 to ₦1,350. The refinery's circular reached marketers late on 11 September.

The association's estimate kept climbing. It reached about ₦1,420 on 14 September before easing to around ₦1,365. The association's 17 September bulletin put import parity at ₦1,364 to ₦1,365, against Dangote's ₦1,350. On 21 September Dangote cut to ₦1,325, which left a ₦40 gap to import parity, Legit.ng reported.

The sequence is a chronology, and nothing published establishes that the refinery raised its price because of the gap. Brent was also trading at about $105 a barrel on 10 September.