1999 Toyota Camry Engine indicator

I stop my carabout 5 months. Now I start back drive. I have already open and clean my engine and change barring. When I driving car moving is good. The heat indicator and all the other indicators are ok. But engine oil indicator is appear and disappear when I was driving. I have no idea about that. I already clean and change engine oil. Pl help me sirl. I have financial trouble. I want to use my car for my families emergency. Thanks a lot Sir.
I will donate next 2 days.