Group II suppliers Motiva, Conoco and ChevronTexaco imposed across-the-board increases of 5 cents per gallon. (Motiva raised its sole Group II-plus posting by the same amount.) Valero left its bright stock posting unchanged but raised all others by 5 cents. Citgo actually lowered its bright stock posting by 5 cents, but raised all others by an equal amount. Sunoco left its bright stock price unchanged, added 2 cents to the posting for its 250 neutral and raised all others by 5 cents.

Motiva, Conoco and Citgo made their changes effective Friday. Valeros went into effect yesterday, while Sunocos goes into place today.

Suppliers and buyers agreed that the price hikes were a reaction to crude oil costs, which had risen by roughly 20 percent since the last round of base oil price hikes, in early July. Crude prices topped $30 per barrel two weeks ago, partly due to fears that Middle Eastern supplies could be disrupted by a U.S. attack on Iraq. The price of crude on the New York Mercantile Exchange lost $1.19 yesterday to close at $27.79 after Iraq said it is prepared allow United Nations weapons inspectors to return to the country.

Marketers contended that the most recent base oil price hikes did not completely make up for the higher crude costs, and said that ExxonMobil had moved conservatively in reaction to unstable crude pricing.

You dont know which way oil is going, one marketer said. As a supplier, you dont want to get whip-sawed raising prices and then having to turn right around and lower them. That doesnt send a clear message to the market.

I think prices could have gone up by 7 or 8 cents, another marketer said. But Exxon moves cautiously on these things. If crude stays in the $29 range, I see [base oil prices] going up another nickel at the beginning of October.

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