I too have a '98 Boxster and I've noticed IF I pause momentarily at the accessory notch (all the dash instruments and radio come "alive") the oil level usually displays for about 10-15 seconds.
However, I've also noticed that occasionally it doesn't , but only occasionally.
Now that you posted, I'll try to keep a closer eye on it and report back......but mine is not an everyday driver so it might be a few days for that report.
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98' Boxster
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