No oil leaks from the engine, and yeah it does seem to. Is it a big job for pistons and rings? I’ve not had to face this with any vehicle I’ve owned. So I have no idea how bad/big a job it would be

hi all, new to this forum and not amazingly mechanically minded. But I understand terminology. My 2.5 TD defender (1988) is drinking oil. Will go through 5 litres every 2-3 months or every 300 miles. I’ve read about the piston rings being a possible culprit. Could anyone else advise on what...