[Whitespeed]

I only just noticed this spring that my lower reservoir was empty and the upper was only 3/4 full. This is after 3+ years of ownership and 12+ track days. No idea what it started at, but I'm assuming it was properly filled from the factory. Coolant does evaporate though, so I'm not stressing about it. I've topped up both the upper and lower and will monitor more closely going forward.

[5.M0NSTER]

I found some info on this in the owner's manual. Page 265.

The bottom tank is a "surge tank" and it is normal for fluid level in that tank to raise and fall with temperature. Fluid can also evaporate out of that tank. It needs to be be re-filled to half way mark level when low.

Just topped mine off.

[Gunkk]

Here you go. Top tank should always be 100% full. Bottom tank half full. Coolant will slowly evaporate over time.

[Baddawg53]

I found the source of my coolant loss yesterday. It wasn't smoking, wasn't leaking, not in the oil. I pressure tested it, checked for combustion getting into the coolant system, everything appeared fine. The issue was getting worse of late, went through about a quart at the track in Sunday. Fingers crossed it's just the head gasket.

[RED HULK]

I had to top off my lower reservoir too. Fill hole is real small. Used a turkey baster with the bulb off and put my funnel in it. Poured pre mix in using a plastic cup.

[weemus]

Originally Posted by funked1

The lower reservoir vents to the atmosphere, so I think it just evaporates.

THIS
I have to add a half gallon a year to the lower reservoir that vents to the atmosphere. Everything else is full and stays so.