Product Description Shell DEX-COOL® Extended Life Antifreeze/Coolant is a single-phase, ethylene glycol based, extended life, universal automotive engine coolant based on a unique extended life carboxylate inhibitor system. Shell DEX-COOL® is suitable for a five year or 150,000 mile service life in automotive applications. In heavy-duty applications not requiring nitrite Shell DEX-COOL® is suitable for a service life of 400,000 miles or 8,000 hours. Shell DEX-COOL® Prediluted 50/50 is a 50/50 volume mixture of Shell DEX-COOL® with deionized water.