Scum in coolant reservoir

[HPRS230]

Whats best when topping up the water tank?
Add
- Tap water
- Distilled water
- Red Coolant
- Other

Mine has dropped alitte

[Umai Naa!!]

For a small top-up, water is fine.

Otherwise, use the correct coolant, which I assume in yours would be G13-spec.

The level does fluctuate depending on how much the system is pressurised. Even if you overfill it, it'll just purge the excess anyway.

[Spinifex]

I can confirm these are afflicted by the same issue with needing to be bled correctly... if there's an air pocket in the cooling system, you will hear the fluid cavitating through the electric water pump, and the reservoir level will drop.... but will bubble and pop & resume normal level when you crack the cap open and equalise the pressure.

And +1 for purging the overflow..... the downside to this, is there's no overflow tube that dangles down so it vents underneath the car neatly..... it purges from an overflow hole in the top of the res, next to the cap... so you get this lovely red stain dripped all over your res, and engine-bay and anything surrounding it.

"Simply Clever" only works 90% of the time