I am looking @ buying a 2012=equinox- shows 32,000 miles 4 cyl, auto - Im curious as to following? what triggers the mileage shown?can the spedo be changed with another that could show low mileage?? or ? what determines the mileage shown? Also - i did notice the oil fill area on top of engine cover had some oil residue-like "blow by?/ not bad just suspect? normal?? also = whts the deal for a tire pressure sender to go off @ 5psi-& can these be changed? expensive? I also noticed the a/c wasnt cold yet compressor was working. Thanx for all replya - just dont want to get stuck with anything expensive for repairs !1