My 2001 Blazer with 130K, been paying a little more attention lately, noticed that at startup and traveling the oil pressure seems to be around 45-50 (analog) but then after several minutes settles in at 40. When just idling it goes lower. Oil has been changed fairly frequently 3-5K but not synthetic. Is this normal?

 

Perfectly normal. Oil is cold (thicker) at start up, so more pressure. Of course, when the engine is at higher rpm's the pressure will behigher than when it is just idling.

 

Yep, normal.