here's a question...

my oil gauge is measured in lbs. per quare inch from 45 (at the top) to 0 (at the bottom). when i'm in idle or stopped, the gauge rests at the top line (45lbs) but as soon as i start driving, it slowly shifts downward and rests just around 30 lbs (the second line). when i took the car in for an oil change and filter change [thanks MB Motors!], it was hanging around 40 -45 for about a week and then is shifted to around 30. does this signify a loss of oil or is this standard? why does it shoot up to the top line (45) when i'm in idle or at a stop sign?

also... i've yet to take the car out on a long freeway drive (longer than 25 minutes) but i'm feeling the transmission thump when it shifts up. granted, i've been doing mostly street driving but the transmission fluid levels are fine. what does anyone out there think may be causing this gentler thump into a higher gear? anyone think it's time to try a TRANS-X deal? or the "italian tune-up" i hear about alot on these boards? or is this something to be expected with stop and start L.A. traffic?

thanks