Is it a problem if the antifreeze is filled to the maximum?
2 Answers
It is not a problem if the antifreeze is filled to the maximum. Here is some additional information: 1. If the antifreeze is overfilled, it may overflow from the pressure relief valve due to thermal expansion and contraction. This is not harmful, but it can leave unsightly stains after drying. 2. Antifreeze usually has an overflow reservoir, which is designed to store excess antifreeze. The reservoir has upper and lower level marks. It is ideal to keep the antifreeze level between these marks, but exceeding them slightly is not a big issue as antifreeze naturally evaporates. However, it is best to fill it to the appropriate level. 3. Try to use the same brand of antifreeze. Different brands may have different formulations, and mixing them can cause chemical reactions between additives, rendering them ineffective.
When I do car maintenance myself, I like to fill the coolant to the brim, but this is actually a mistake. The cooling system expands when the engine is running, and if it's overfilled, the excess fluid can easily spill out from the overflow port, dirtying the engine bay floor and potentially corroding other components, leading to issues like short circuits in wiring. Doing this long-term can cause excessive pressure that may damage the radiator cap or hoses, and engine overheating problems can follow. I remember checking last week—after filling past the MAX line, as soon as I drove off with a warmed-up engine, coolant gushed out. Luckily, I pulled over without any incidents. It's best to keep the level between MIN and MAX for peace of mind and hassle-free maintenance.
