I pumped up the system to 10 psi and observed a hairline leak in the auxiliary reservoir. My question is, is it reasonable for me to drive before fixing it?

I did use RTV blue to coat the region of the hairline (which is along the central ridge that separates the upper and lower halves). I question whether that will seal it, but am letting it cure before I retest it. I have a road trip next week and would really like to take the Merc. My other leaks seem to be resolved at this point (and they were more like at 5 psi and from the gaskets).

I am really glad I bought this radiator pressure tester. Its really helpful to see where I have leaks before filling the radiator system!

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dannyf
1984 Mercedes 300 SD 214 K miles. Runs on WVO ~ 22 mpg over 8 K on WVO
1997 VW Passat TDI 156 K miles. Uses biodiesel and diesel. ~ 41 mpg
1996 Mercury Villager gasser. ~ 20 mpg