Eta Carinae is one of the most luminous and mysterious known binary star systems. Located only 7,500 light years away, multi-wavelength observations reveal that Eta Carinae is a massive (~120 MSun) colliding wind binary system containing a Luminous Blue Variable (LBV) and either a Wolf-Rayet or extreme O star in a highly eccentric (e = 0.9), 5.54-year orbit. We present results from a new time-dependent, full three-dimensional (3D) hydrodynamic simulation of Eta Carinae and its colliding stellar winds around periastron, performed using the grid-based adaptive mesh reﬁnement (AMR) code RAMSES. We focus on the time-varying behavior of the wind-wind collision (WWC) region’s density, temperature, velocity, and geometric structure. The results show that this grid-based AMR simulation greatly improves upon past simulations performed using SPH methods, particularly in terms of resolving various physical instabilities that arise within the WWC zone that are import for explaining various observational diagnostics, such as the peculiar minima in the multi-epoch X-ray light curve. By directly comparing the simulation results to available and future observational data, we hope to further constrain the various orbital, stellar, and wind parameters of Eta Carinae and provide insights into the late-stage evolution of massive binary systems.