What did I do now?

[Bala]

Have a habit of reading instructions AFTER.

Poured some Prestone coolant to top off the level - was at or slightly below min level. Might have put in about 1/4 - 1/5 quart. Coolant flush is in the to-do list but, do am I looking at a immediate action item or can it wait? Not driving much as I have to change the plug tubes, sensors etc to get it inspected.

Also do I have to put only Porsche stealership coolant or can I get an aftermarket for less?

2000 Boxster S

Thanks.