Oil light on lifters are clattering on 1994 Land Rover Defender 90

I had stored my rover for three years and it ran fine then,but recently when i started it the oil light came on and the lifters are clattering,it maybe something else clattering im not sure.I changed the oil and cranked the motor with coil wire off to circulate the oil before i started it.could my oil pump screen be clogged from the car sitting so long?

Asked by for the 1994 Land Rover Defender 90
have an oil treatment cleaning done and see if that helps
Do you mean just running motor flush through it and changing the oil?do range rovers use a synthetic oil?
ck in your owners manual or call local parts house they will know