Pentachlorophenol (PCP), in a variety of petroleum carriers and solvents, was used in 3/4-inch stake tests at the Bainbridge, Georgia test site. Performance comparisons were made of the treated stakes, as affected by 5, 7, and 10% PCP concentrations in 9 different petroleum oils and oil blends. In all instances where P9 type oils were used, the stakes were treated with a 5% concentration. The physical and chemical properties of the oils are known to have a determining effect on performance. Alcohol, aldehyde, amide, ketone, and ether solvents were used as cosolvents with a toluene diluent in the treatment of 9 series of stakes with PCP. The performance of stakes was compared for the effect of wood swelling properties and solvent properties on service life. Comparisons were made with toluence, a phthalate, and other anti-blooming type cosolvents. The effect of these properties on service life is discussed. -- AATA