Abstract
Ten samples of premium motor spirit were collected at different dispensing points and analyzed to determine the extent at which the adulteration of this petroleum product affects automotive engines. Results of the analyses shows, research octane number values from 60.10 to 93.30, specific gravity from 0.7523 to 07885, Reid vapor pressure from 0.28 to 0.60 kgf/cm2, while atmospheric distillation ranges from 189 to 251°C. The result of this research reveals that most of the products are highly adulterated and this is not desirable for spark-ignited engines, as it may lead to the problem of detonation, insufficient supply of engine power, slow rate of deflagration experienced by most consumers, and consistent knock of spark-ignited engines.