100 miles a day...I'm lucky if I get that in a week or so. You will find many opinions on tires if you search...as far as oil, please read the following information on LN's website; the engine you save, may be your own.
http://www.lnengineering.com/oil.html
FWIW, I run Castrol Syntec 10W40 and only drive in moderate to warm temps.