If you borrow someone’s car, should you fill up the tank?

[Sniped]

What is the general ‘rule’ here?!

Say it’s 2 longish return journeys about 2-3 hours each.

I don't understand why, if they have their own car, they need to borrow yours?

I wouldn't expect it to be filled up, but I'd expect it to be returned with the same amount.

Person in question IMO takes the absolute piss in other ways (lives with us rent/bill free, doesn’t clean up), for some reason this is the hill I’ve chosen to die on!

While you're pissing them off, I'd also be tackling why the parent AND your husband feel this is acceptable too. The living rent and bill free is, I suppose, valid IF it is a joint decision and family funds can support it - but not clearing up after themselves ... nope! Time to tell the parent you are not their skivvy and demand that your husband supports you.

[quote Sniped]@HollowTalk no, his parent![/quote]
Leave the car empty. When s/he has anything next time they want to borrow it - be clear. You've used it for weeks and not put a drop of petrol in it - its about time you filled it.

@Sniped

I know I need to find a back bone.. I’m very lacking in that department. And at almost 30 I don’t really know where to start with gaining one.

Start by saying no. As a complete sentence.

I used to borrow my parents car for a month each summer.
It got returned with a full tank (of the expensive Petrol they said it needed), valleted and the scratches they had put in it in the previous year buffed out.

The feel entitled because they decided to have a child. So now that child owes them, and so does everyone associated with him. I would be kicking the narc parent out of my house so fast their feet didn't touch the ground.

Yes fill up it's only after use 🙂