I've noticed a decline in oil pressure in my car lately. Driving down the road at 60, the gauge shows around 25-30 lbs of pressure. It used to hover around 40 after it was warmed up.
My dad said changing the main bearings could fix the problem. Does this involve a significant amount of work? Cost?

 

yes, you pretty much have to have the motor out...

 

That does not seem like bad pressure. What is the presure at idle? 15 psi is good at idle.

 

i agree, the oil pressure may be lower, but its not necesarily bad...it could be a number of things, but your main bearings have nothing to do with it, the CAM bearings are where your oil pressure comes from...either one (cams or mains) you replace, it will be a pulling out the motor job, if i were you, id start simple, possible and oil pressure sending unit? if not that...then maybe the oil pump itself, id only resort to bearings as a last thing id do