It is well known that the addition of a second ion population into a proton-electron plasma gives rise to new low-frequency wave modes. Here we investigate stationary structures streaming with sub-fast speed in such a bi-ion plasma. It is shown that a new type of stationary structure occurs as result of mode splitting effects caused by the second ion population. These so-called 'oscillitons' are characterized by an oscillating spatial structure super-imposed on the spatial growth or decay associated with the usual single-ion solitons. Examples of the solution of the full non-linear equations describing stationary bi-ion flows are given which show that 'oscillitons' may contribute to a better understanding of diverse low-frequency phenomena observed in the mass loaded plasma environments of Mars, Jupiter and comets. ¿ 2001 American Geophysical Union