NOVELTY - The coolant with variable heat capacity for cooling of combustion engines (4), fuel cells and batteries, comprises 5-45 wt% of microcapsule phase change material (PCM), below 1% of water, non-aqueous coolant, oils, additional corrosion inhibitors, micro capsule corrosion inhibitors, dehydration agent and/or micro capsule dehydration agent. The oil is silicone oil, mineral oil distillate, mineral oil raffinate, synthetic oil, biological oil and/or mixture of 20-30C alkanes. The boiling point and heat capacity of the coolant are above 125degreesC and 1-3 kJ/kgK respectively.    USE - Useful for charge-air cooling, retardant cooling and exhaust gas recirculation cooling, and also for cooling of internal combustion engines, batteries of hybrid vehicles or fuel cell in fuel cell vehicles (claimed).    ADVANTAGE - The coolant has small thermal capacity and specific heat transfer, reduces cavitation and friction of the engines, protects the engine from corrosion and improves heat management of the combustion engines.    DETAILED DESCRIPTION - The coolant with variable heat capacity for cooling of combustion engines (4), fuel cells and batteries, comprises 5-45 wt% of microcapsule phase change material (PCM), below 1% of water, non-aqueous coolant, oils, additional corrosion inhibitors, micro capsule corrosion inhibitors, dehydration agent and/or micro capsule dehydration agent. The oil is silicone oil, mineral oil distillate, mineral oil raffinate, synthetic oil, biological oil and/or mixture of 20-30C alkenes. The boiling point and the heat capacity of the coolant are above 125degreesC and 1-3 kJ/kgK respectively. The PCM in solid or liquid condition shows a heat capacity of 1-3.5 kJ/kgK. The phase change material is present below its melting point in fine suspension or emulsion and is formed by paraffin, synthetic polyethylene or sugar alcohol. The PCM is an organic salt or an organic compound with melting temperature of 65-115degreesC and shows fusion heat of 150-400 kJ/kg. INDEPENDENT CLAIMS are included for:    (1) procedure for heat management of combustion engine; and    (2) a coolant circuit for internal combustion engine.    DESCRIPTION OF DRAWING(S) - The figure shows a coolant circuit for internal combustion engine:    Cooler; (1)    Pump unit; (2)    Supply line; (3)    Combustion engine; (4)    Conduit. (5)