Since the establishment of crude oil refining, refiners have encountered the problem of fouling in heat exchanger trains, heaters, and atmospheric and vacuum distillation columns. Crude oil fouling is one of the major problems that triggers efficiency reduction, environmental impact, unplanned shutdown, and loss of revenue and yield. In the topic of crude oil fouling, most published papers were focused on heat exchanger fouling and, to a lesser extent, the distillation columns and heaters. However, with the absence of a vacuum column, some small refineries operate and flash the crude oil at or above 700 degrees F for better recovery. In this study, a simple and affordable bench-type research laboratory rig was fabricated and used for the determination of the gravimetric fouling deposits for several crude oils and blends at an elevated temperature of 720 degrees F or more. To address the high-temperature impact on crude oil fouling, the Delta API and Delta microcarbon were used to indicate the extent of the thermal cracking. Ultraviolet-visible spectroscopy was used to detect the increased aromaticity of agglomerated asphaltenes and resins as a result of the possible self-association at higher temperatures. At a higher temperature, the thermal cracking is much greater than that at 580-620 degrees F and the fouling could take on different mechanisms.