Hey Nick,
Every 3-4.5k for your higher mileage car is fine, but, IMHO, I would lean more towards 3K if it's your daily driver (especially since it's NOT your average car

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looks like my response came after you already answered your question. Anyway, always glad to see higher mileage Boxsters & other vehicles being well-maintained!
Hey Unkle, congrats on your Bronco! Nice! My Explorer is close to 140K and I'm hoping that it does the same and then some!