A broad literature on how oil wealth affects civil war onset argues that oil production engenders violent contests to capture a valuable prize from vulnerable governments. By contrast, research linking oil wealth to durable authoritarian regimes argues that oil-rich governments deter societal challenges by strategically allocating enormous revenues to enhance military capacity and to provide patronage. This article presents a unified formal model that evaluates how these competing mechanisms affect overall incentives for center-seeking civil wars. The model yields two key implications. First, large oil-generated revenues strengthen the government and exert an overall effect that decreases center-seeking civil war propensity. Second, oil revenues are less effective at preventing center-seeking civil war relative to other revenue sources, which distinguishes overall and relative effects. Revised statistical results test overall rather than relative effects by omitting the conventional but posttreatment covariate of income per capita, and demonstrate a consistent negative association between oil wealth and center-seeking civil war onset.