because it wasn’t advertised as a chevy engine
The soaring popularity of Oldsmobile vehicles resulted in a major issue in the late 1970s. At that time, each General Motors division produced its own V-8 engines, and in 1977, Oldsmobile, Chevrolet, Pontiac and Buick each produced a unique 350 cubic inch displacement V-8. The popularity of Oldsmobile models caused demand to exceed production capacity for the Oldsmobile V-8, and as a result Oldsmobile quietly began equipping some full size Delta 88 models and the very popular Cutlass/Cutlass Supreme with the Chevrolet 350 engine instead. Although it was widely debated whether there was a difference in quality or performance between the two engines, there was no question that the engines were different from one other. Many customers were loyal Oldsmobile buyers who specifically wanted the Rocket V-8, and did not discover that their vehicle had the Chevrolet engine until they performed maintenance and discovered that purchased parts did not fit. This became a public relations nightmare for GM. Disclaimers stating that “Oldsmobiles are equipped with engines produced by various GM divisions” were tacked on to advertisements and sales literature. GM quickly stopped associating engines with particular divisions, and to this day all GM engines are produced by “GM Powertrain” (GMPT) and are called GM “Corporate Engines” instead of GM “Division Engines”. Although the popularity of the Oldsmobile division vehicles prompted this change, declining sales of V-8 engines would have made this change inevitable as all but the Chevrolet version were eventually dropped.