Oil buzzer unless I'm revving it

I nick them from MK3 golf in the scrap yard, recycling is good

for the earth cable the chassis earth ring in the middle wont reach the chassis leg hole. So what I do is grab 2 earth cables and chop the 2nd one down so you have a length of cable with ring terminal either end. put one end to the main earth middle ring with a nut and bolt, other end to the chassis leg.

note how the mk3 earth goes to a stud on the upper bolt holdign the gearbox to the engine, this is a much better earth point so grab the bolt as well. the mk1 earths to the top of the gearbox bracket, its not great since corrosion builds between the box and bracket over time

Thanks Briano1234 and rubjonny .

I earthed the blue/black wire off the high pressure oil sensor to the negative earth battery and the light/buzzer didnt come on.

So potentially my earths need cleaning and changing.