I had this problem a month ago
The car was runing fine when cold, whean it warmed up the oil and stop light was coming up, when reving over 1500rpm it goes out. I was thinking the oil was to thin (previously elf 5W30) filed up with a thicker oil 10W60 and the car was running fine. But when it got to the cambelt change few days ago, I told the mechanic to fit the new cams I bought form CatCams.
When they opened the cylinder head, the cam bearing journals were totally worn off :/ since I was not able to find the head alone in good price the only way was to find a new engine.
I would consider the possibility You car is suffering the same