My hometown local PD, Fire, emergency search and rescue, and local (not county) plow trucks use/used (last time I was in the shop) Kendal Super DXA 15w40 in everything, from city cars to cop cars to plow trucks, all drawn from either totes with a pump or 55 gallon drums on a drum caddy also with a pump. Absolutely everything got bulk 15w40 conventional. Filters were a mix of Car Quest, Parts Plus and Napa depending on the application. HD diesel filters were mostly Car Quest Baldwin filters, passenger car police and light truck were wither Napa Pro Select or Parts Plus value filters.