Two primary types of insulating sleeves have traditionally been applied in the thermal protection of automotive hoses and cabling; braided and sewn. Automotive engineers would benefit from understanding the effects of different sleeve types and fit characteristics on thermal performance. A design of experiments was conducted examining the effects of sleeve diameter, sleeve surface emissivity, and sleeve to hose orientation on the heat protection characteristics of an insulating sleeve in an underhood hose application. The temperature data collected showed that, while surface emissivity had a major effect, sleeve diameter and orientation had no significant effect on sleeve performance. Some guidelines are presented to allow engineers to make sleeve selections within the scope of the test. The study will be continued to broaden the scope of the guidelines and establish a theoretical model.