Neighbour's tree - root damage

Your over thinking it your oil line isn't made of glass its a copper pipe that will bend, roots aren't going to damage it.

You have bad neighbours I get that but this isn't a way you can get at them.

You can't take them to court for any damage as they don't own the property afaik you'd have to go after the owner.

I feel your pain and you have my sympathies, we could all be cursed with bad neighbours at any time

If, and it's a huge IF, you have issues with damage from tree roots then it's the owner you have to deal with. It has nothing to do with the tenants.

But you're not posting unhelpful comments are you? You should have said "I just ask stupid questions in forums".

Not legal advice - just a few observations on general principles.

1. Irrespective of the material from which the oil line is made, tree roots, if strong and big enough, may well break it. It is well known that tree roots can strangle or break underground services including electricity, comms, water, sewerage and anything else in the ground.
2. Trespassing tree roots are a potentially serious problem and not just for underground services. If big enough and strong enough they can abstract water and create undermining of foundations. That seems a long way off here and would depend on a number of factors. The problem is that unless they break the surface you cannot see where they are !
3. If the oil line, or anything else, was damaged by strangulation by trespassing roots there is a stateable case against the owner and or occupiers. Much would depend on what terms they have in a lease as regards maintenance and such matters but that is between them.
4. Normally, claims like this would be against the occupier of property on the premise that the occupier enjoys control of the property. However, there might be a liability on the landlord owner too.
5. Check your household insurance policy to see if it provides any cover in respect of damage to underground services. Some provide cover for repairing accidental damage to such services but I don't know if they would cover remedial works for the polluted ground or the cost of replacing the lost oil. It depends on what the policy covers.
6. In the event of a loss due to tree roots trespass the OP's house insurance might cover some or all of it. In that event the insurers then become entitled to go against the owner or occupier to recover outlay.
7. Be exceptionally careful about cutting trespassing roots as you cannot know what unintended potential consequences could follow from that. For example, you could cut roots, the present occupants depart, the tree dies and falls on one of the new people. Always take professional advice before embarking on that road.
8. Poisoning the trees is a really bad idea as that may well constitute criminal damage.

Despite previous problems I would make one further attempt to get the owner's details from the tenants. I know what you expect to be told to do but it would be worth it to try and abate a potential problem in good time.

Good luck with it.

It is important in a case like this not to let the grass grow under your feet!