2006 C2S, 59,000 miles. Tank, cap, thermostat and pump changed a week ago. Perhaps I'm too paranoid or my eyes are playing tricks but the coolant when the car is cold is orange but pink when hot?

Yesterday before adding more coolant. Notice the orange-ish color at the bottom of the tank:



Sample of the tank this morning (top) vs fresh 50/50 coolant (bottom):



When the car is hot after a ride:



I noticed the color this spring before taking the car out of storage. The previous shop I was going to is using G13 pink coolant and the current one as well but they didn't do a complete flush when they worked on the car last time. I've been adding coolant I bought from Porsche.

Can older pink coolant turn orange when old?

Thanks!

 

A quick test kit (dip strip) will solve this dilemma, just grab one from an auto store. I recall when I changed my coolant that was 10 years old, the new color was lighter rather than deeper.

 

Thanks. I'll give the strips a try but I'll have the whole system flushed as I believe it has never been done in 17 years. I should've asked the tech to do so instead of assuming he would.

 

I got some test strips and the coolant seems ok (pH 9, Glycol 60%).

After a ride the coolant in the tank was pink but 2 days later it's now orange. What's happening?

I'm having an appointment to flush the system but I'd like to know what could be causing this and if it's a concern or not.

Thanks!

 

2009 C2S 189K miles

I never heard of color changes with temp changes. However, per my friend at Ford, he noted that coolant will turn darker as it ages as the active ingredients such as corrosion prevention chemicals are used up. When I changed my coolant at around 158K miles, it was dark cherry red compared with the more pink color of new fluid... so darkening with age appears to be true. IMO, changing coolant should be done at 100K miles.... why? I dunno, seems that way to me.

Peace
Bruce in Philly (now Atlanta)