MB coolant is gold, same as Zerex G-05, and available for $15 (even from peachparts...), not sure why everyone always claims its really expensive. My WP failed last year and it gushed...pretty much equivalent to pouring a bottle of water constantly. Amazing I even made it home in fact (had about 30 gallons of water in back just in case). A reseal fixed the issue and wasn't too hard...been holding since. 8 months seems pretty short, I'd pressure test the expansion tank cap if possible to make sure there isn't extra pressure on the system.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth