oil light

So here we go for my 2nd forum post ever lol I just purchased my 07 Nitro SXT 4wd from a previous owner... and today my oil light came on.. but only when my rpms dropped below 1000 h once its over 1000rpms it turns off...I just replaced the battery today also bcuz I took it to get tested n it...

My wife had the oil changed about 3 weeks ago on her Nitro and we started having a slight "dry" start in the mornings, pretty much immediately(Damn Valvoline!!)...I checked the levels and added some Lucas oil additive. About 4-5 days ago the oil light started coming on intermittently while...