I'd find a better screwdriver....

The pro series sears (smap-on's) will fit the screw properly. They have a hex boss at the base so you can slide a wrench on. Push hard with arm, use the wrench to break the screws free.

If the fluid wasn't really dirty, I'd wait a while. Heck, you did the hard and messy part with getting all the old fluid out. On mine, I can remove the ??drivers side cooler line and drain another 1/2 quart or so.

Michael

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Michael McGuire
83 300d
01 vw A4 TDI
66 Chevy Corsa
68 GMC V6 w/oD
86 300E