Oil light flickering

[Lisab]

Hi! I have a 1.4 Astra 1997. Recently bought it. It’s very clean. But the engine management light comes on often, I’ve noticed it comes on more if I have to put E10 in also it’s missing and it loses power..but that can happen even with E5. Today the oil light has started flickering checked the oil but there plenty in it, I did too up just in case..still light comes on. Any ideas please