Do you add oil between oil changes?

[mnc-i]

I have never had to add oil to my 1999 Boxster.

I purchased it in Sep 2009, with 104,000 miles.

I change the oil & filter every 10,000 miles.

I started off using Mobil 1 10W40 and for the last few changes I have used Mobil 1 15W50.

I now have 194,000 miles.

MNC-I