How to Add Coolant to a 2015 Mercedes C300 - Fix Low Coolant Warning, by TheRenderQ on YouTube. 2 min 35 s.
- Video length
- 2 min 35 s
- Time to do it
- 15 minutes
- Difficulty
- Easy
- Steps
- 8
What you need
Steps
Park on level ground and let the engine cool completely. Do not touch the coolant cap while the engine is warm, since the system is pressurised and can spray hot fluid.
Open the hood and find the coolant reservoir. On the W205 C300 it sits near the front of the engine bay with a cap marked with a coolant symbol.
Check the level against the min and max marks on the side of the reservoir. If it sits at or below the min line, it needs topping up.
Mix concentrated coolant with distilled water at a 50/50 ratio in a clean jug. Skip this step if you bought pre-mixed coolant.
Slowly unscrew the reservoir cap. Place a funnel in the neck and pour coolant in until the level reaches the max mark.
Wipe up any spills with a rag and screw the cap back on firmly. Coolant is slippery and toxic, so clean up drips and wash your hands.
Start the engine and let it idle for a few minutes, then switch it off and let it cool again. Recheck the level and top up if it dropped.
Drive the car normally. The low coolant warning should clear once the level is correct, though it may take a short drive or a restart.
Tips and common mistakes
Never open the coolant cap on a hot engine, since pressurised hot coolant can cause serious burns.
Use only the coolant spec listed in your owner's manual for your exact year and engine, as Mercedes changed formulations over time.
Always mix concentrate with distilled water, not tap water, to avoid mineral buildup in the cooling system.
If the level keeps dropping after a top-up, you likely have a leak and should have the system pressure tested.
Questions
Can I use any pink coolant from the auto parts store?
Not safely. Mercedes used several coolant formulations, so check your owner's manual or ask a dealer for the correct spec for your car.
Why is the low coolant warning still on after I topped it up?
The message can stay until the car registers the new level, so drive a short distance or restart the engine. If it returns, the level may still be low or you have a leak.
How much coolant should I add?
Add only enough to bring the level to the max mark, usually a small amount for a top-up. Do not overfill past the max line.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
