The mass of deposits at steel surfaces and the dynamic viscosity were measured at 10-45 degrees C in model oils (toluene + vacuum residua) with 12.3 g/L asphaltenes. The observed steplike changes of measured parameters at similar to 27 degrees C were interpreted as indicative of a first-order phase transition to reduced particle volumes in asphaltene colloids. By a number of specific features this transition resembles well-known phenomena at the lower critical solution temperature (LCST) in thermally responsive microgel dispersions of block copolymers. The microgel/LCST analogy is further supported by literature data on the structure of basic asphaltene nanoaggregates. In particular, a comparative asphaltene-microgel discussion shows that the role of hydrogen bonding in primary asphaltene aggregation may be underestimated.