Ergon plans to raise all its naphthenic oils by 20 cents/gal on June 9.

Cross Oil said it will push up prices on its lineup of pale oils by 20 cents/gal on June 12.

On June 15, San Joaquin Refining will adjust its naphthenic grades upward by 20 cents/gal.

Steeply rising operating costs alongside depleted margins were the main justification for this round of price hikes, suppliers said.

In the meantime, the base oil supply/demand situation remains largely on target with customers orders meeting suppliers expectations. In some downstream segments, demand is deemed stable to improved, while consumption in other end-use areas remains soft. Sellers reiterated that sales have outstripped previous months since the beginning of the year, and May sales were significantly improved over March and April volumes.

In upstream news, on Tuesday crude oil values touched seven-month highs at over $69 per barrel during intra-day trade, while global stock markets surged and the U.S. dollar weakened. The last time oil prices reached this level was in November, when oil traded around $70/bbl.

The 12 member countries of the OPEC cartel voted on Thursday, May 28 in Vienna to maintain oil output at current levels, rather than increase supplies in order to bring some relief to consumers, particularly in the gas-guzzling West.

According to news reports, oil ministers from the Organization of the Petroleum Exporting Countries, whose countries account for about 40 percent of the world’s entire crude oil supply, also renewed their commitment to stick to their agreed quotas, rather than ship extra oil, as they began doing last April when several members ignored their agreed output limits.

Energy and oil analysts believe OPEC’s decisions on Thursday could help push oil prices even higher.

If the U.S. and other major industrial economies rebound, oil supplies could be depleted because the recession has prompted producer nations to freeze hundreds of projects to open new oil wells or upgrade existing ones, analysts said.

Global stock markets also rallied this week. In the U.S., on Monday, The Dow Jones industrial average shot up 221.11 points, or 2.6 percent, to 8,721.44. The Standard & Poor’s 500 Index gained 23.73 points, or 2.58 percent, to 942.87. The Nasdaq Composite Index jumped 54.35 points, or 3.06 percent, to 1,828.68.

As stocks surged, Treasury prices fell and the dollar weakened. Government debt and the greenback are both perceived as investor safe havens, but as recovery hopes gain strength, investors move funds into higher yielding assets.

The weakening dollar boosted oil prices. Crude is traded in the U.S. currency around the globe, and so a weaker dollar pushes the prices of oil up in relation to other currencies, according to specialists.

On Tuesday, stock markets lost much of their upward momentum even though they turned positive after choppy sessions. At the closing bells, the days settlements did not measure up to the substantial gains seen on Monday, but both the Dow and other major indexes were at fresh highs for 2009.

Looking at related-business news, in press releases issued by Holly Corp. and Sunoco on June 1, the companies confirmed completion of the sale of Sunocos 85,000 barrels per day refinery in Tulsa, Okla., to Holly Refining & Marketing. The facility includes a 9,500 b/d Group I base oil plant. The Group I price chart below has been amended, with Holly replacing Sunoco.

At the close of the Tuesday, June 2, NYMEX session, light sweet crude futures ended the day at $68.55 per barrel, a sizeable gain of $6.10 /bbl compared to the settlement reported one week earlier at $62.45/bbl.

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