01/09/2026
Clogged heater cores can be caused by a number of issues. Lack of cooling system maintenance, mixing different coolants, and adding stop leak.
Many people may over look maintenance of their cooling system. The frequency varies widely between , vehicle manufacturer recommendations, and coolant manufacturer recommendations. This Typically falls between 30,000- 100,000 miles OR every 2-5 years.
It is important to know the type of coolant your specific vehicle takes. Today there is an "all makes coolant" which does cover a variety of cooling systems, But every cooling system is made up of different types of materials.
This is why there are a variety of coolants with different additives.
When you mix coolants, they can react, creating sludge, that can clog parts of the system and create corrosion.
Why not use stop leak additives ?
While stop leak additives may create a temporary fix, they can create bigger problems. Mainly clogging up parts of the cooling system.
We NEVER recomend using these products. A minor coolant leak repair, could turn into more major repairs by doing this.
*Pictured is a clogged heater core one our of technicians cut open.
