The cloud-point pressures for a three-arm-star polyisobutylene (4K) in ethane, propane, dimethyl ether, carbon dioxide, and chlorodifluoromethane were measured in a variable volume optical cell up to 200 degrees C and 2000 bar. These pressures, presented as LCST and U-LCST curves, are found to depend strongly on the size difference and polarity difference between solvent and polymer. The cloud points measured in this work confirm the aggregate size estimated from the statistical associating fluid theory (SAFT) for CH3-PIB-OH (1K) and HO-PIB-OH (1K).