The 60,000-ton parcel is for lifting on March 28-April 3 from the joint-venture Samref facility, on a free-on-board basis. The facility usually sells 650-cst high viscosity barrels.
Offers for the cargo are expected by Tuesday and a deal is expected to be concluded a day later.
Traders said the reason for the rare offer is probably because the plant is undergoing scheduled turnaround from late March for 45 days until early May.
"It's probably surplus cargoes that they would otherwise have used domestically but need to sell because they flushing the tanks for maintenance," a Singapore-based Middle East trader said.
"We're not clear what the specs are, other than it is 380-cst, because they haven't told us. Let's wait and see."
The 400,000 barrels per day (bpd) Yanbu refinery, which Aramco jointly operates with ExxonMobil, typically exports five 650-cst parcels every two months, but volumes are expected to fall during the turnaround period.
Aramco has sold three March-loading parcels, totalling 300,000-350,000 tons, down from 500,000-550,000 tons for February-loading, largely due to the turnaround.
The fall in supply has had an impact on the Fujairah marine fuels market, which has seen bunker prices above Singapore values by $10.00-$12.00 a ton in the past 1-2 weeks, from typical levels of around parity.
The tightness has also seen cargoes from the Middle East and West Coast India being drawn into the region at significantly higher price levels in the past two to three weeks.
Aramco last sold a 380-cst lot, for lifting on March 21-23 from its joint-venture Sasref refinery with oil major Shell in Jubail, at a discount of $5.00-$6.00 a ton to Singapore spot quotes.
However, the East Asian market remains heavily supplied, with April volumes of 3.5-3.6 million tons, the highest since December last year.
Reflecting the weakening market, the product's prompt crack stayed at discounts wider than $6.00 a barrel for the first time since October, valued at minus $6.34 a barrel at midday.
