My 12 year old female cat has recently started pooing ever 3 or 4 days when she previously had a daily habit.
It's always very dry and small amounts.

She seems as healthy and happy as ever..should I be worried about this?

I was thinking about putting a little olive oil or cod liver oil into her food to help things along.
Is it okay to do this and, if so. how much?

This happend to my cat, after her eating dry food, i just put bits of water in her wet food and seemed to sort her, i personally wouldnt use oil might not agree with your cats tummy, try some cat milk also might help

She NEVER drinks water from her bowl ( I swear in the 2 years I've had her I've never seen her drink) so maybe adding a little to her food might work.

She only eats wet food,with an occasional sprinkling of Go Cat on the top,but not every time.

She does eat a lot of those 'Dreamies' things though. She's like a drug addict with them and I'm afraid I indulge her

Another thing which may be relevant....
She's a long haired cat and I've very rarely seen her regurgitate a hairball ( maybe twice in the two years I've had her)
I wonder if she may be clogged up with hair.

http://www.amazon.co.uk/Katalax-Cats...ywords=katalax

I used olive oil to get my dog going after surgery but I don't think I would use it as a long term solution, unless the vet advised that it would be OK.

Give them a ring and ask.

Are you sure she's struggling, not just going elsewhere? We used caster oil for our cat who often got completely bunged up due to a medical condition, it was great stuff, but don't tell the chemist it's for a cat. Just a tiny amount will help ease things, but I'd check she's not finding alternate toilets first.

I give my cat half a tin of tuna in oil when he gets bunged up..always seems to work!