2006 Yukon Denali XL Low Oil Pressure

[Cowhead]

I have a problem with Low Oil Pressure on start up and it seems like it only does it when its cold out. I start it up and it it dings like crazy for Low Oil Pressure. The motor makes no sounds or seems stressed at all and after a min or two of running depending on how cold out side it is 32 to -30 it will slowly climb but than it will drop out again and it will say LOP and than it will rise again and it will do this for a while. Once the vechicle is warmed up it runs at about 40PSI so any Ideas on what this may be... is it an Oil Pump issue or a Oil Pressure switch issue? I run 5-30 Mobile 1 Syn and Lucas with a WIX Filter...

 

[salmna0b]

you have to fix the problem as soon as you can. mine did that, it was the oil pump, i ignored it n later paid for may mistake, the rod bearing got damaged, the cylinder got cracked...
you could try lighter oil 5w20, if the problem is still exist, then u gotta change the oil pump

 

[Cowhead]

So what was the over all cost of having that replaced and how long did it take them to do it?