While there were differing reports about the amount of the increases, sources said that some of the cuts had moved up by a few cents to 20 cents per gallon, with the heavy-viscosity grades experiencing the steepest hikes.

Within the Group I segment, appetite for bright stock appeared to be very healthy, and numbers for this cut have moved up significantly, according to sources. There has been particular interest from European buyers, as bright stock was understood to be in limited supply, and export indications have therefore climbed.

Bright stock availability has dwindled on a global scale due to the rationalization of Group I facilities, and demand is expected to outstrip supply in coming years, explained Jamie Brunk, manager for lube studies at HSB Solomon Associates, during a presentation earlier this week at the American Fuel & Petrochemical Manufacturers International Base Oils and Waxes Conference in San Antonio, Texas.

Brunk predicted a supply shortage of bright stock of approximately 6,000 barrels per day by 2025, adding that the decline in bright stock production is the result of an economic question, rather than a capability question as some of the newer plants, such as Group II facilities, could potentially produce bright stock.

Bright stock is not produced in some of the new hydroprocessing units because refiners have made an economic decision not to add or retain the required solvent processing units. The process of producing bright stock is more expensive than making solvent neutrals because it requires an extra step of solvent deasphalting, he noted.

Some refiners have also adjusted production away from the light grades toward higher value heavy-vis cuts and bright stock, Brunk added. Based on Solomon data for 2014, existing refineries could increase bright stock production by 9 to 10 percent, using underutilized capacity.

Aside from bright stock, other heavy cuts are equally difficult to find in sizeable volumes for spot transactions, as producers are concentrating efforts in meeting contractual obligations.

A U.S. facility is undergoing maintenance at present, while two more plants are expected to be taken off-line in the next few months. Producers were heard to be building inventories to cover requirements during the outages, restricting availability of spot cargoes.

In the Group II category, the Excel Paralubes plant in Westlake, Louisiana, was heard to be currently completing a routine turnaround, while Chevrons Group II plant in Pascagoula, Mississippi, is slated to start a turnaround in April.

A maintenance shutdown is also scheduled at Ergons plant in Newell, West Virginia, in late March/early April; and a turnaround at one of Motivas three base oil trains at its Port Arthur, Texas, refinery is expected in June.

Additionally, there are several facilities in Singapore, South Korea, China and Japan that are either shut down, or will be idled in coming weeks, while the ongoing shutdown at the Shell-Qatar Petroleum GTL Pearl facility in Ras Laffan, Qatar, is taking significant amounts of Group III out of the market.

The outage provided extra support to the recent posted price increases for Group III cuts in the U.S. and is pushing spot indications up as well, sources noted.

Upstream, crude oil futures strengthened on Tuesday, on disruptions in Libyan crude production and talk of a six-month extension of the agreement among OPEC members to curb crude oil production.

West Texas Intermediate futures on the CME/Nymex settled at $48.37 per barrel on March 28, up $1.03/bbl from the March 21 settlement of $47.34/bbl.

Light Louisiana Sweet wholesale spot prices closed at $48.87/barrel on March 27, compared to $49.64/bbl on March 20, according to data from the U.S. Energy Information Administration.

Brent was trading at $51.33/bbl on the CME on March 28, up 37 cents/bbl from $50.96/bbl on March 21.

Historic U.S. posted base oil prices and WTI and Brent crude spot prices are available for purchase in Excel format.