Mobil 1 users

[mark werner <wermar19@mirage.skypoint.com>]

I have an '87 4kCSq with 130,000 miles on it. I purchased the vehicle at 82,000miles.
I have changed the oil at 3,000/3month intervals using traditional oils. At the 130,000 
mark I used Mobil 1 for the first time. What I am wondering about is drain intervals. The 
car is driven about 10,000 miles per year. Can I change oil and filter at 6 month intervals 
without fear?
  My mechanic says my engine is one of the cleanest he has ever seen and I would like to 
ensure its flwaless (so far) performance. Any comments from fellow Q-heads using 
Mobil 1 would be great.
  Living in MN I was planning on using the 15W-50 from March to September and the 
10W-30 from September to March.


Thanks,
Mark