want to paint the inside of my garage.its currently rendered on the inside over brick,i have alot of normal white paint, for indoor use etc, if i add some water to it, will it adhere o.k and last to the masonry ?

its sittin there doin nothing,10 litres so tought why not use it

cheers

As it's unlikely to be affected by the weather, then it should be ok to use.

If you thin it down you'll probably find it will take loads of coats to get a good solid colour. Render that has never been painted will really suck in the moisture from the paint and give a very patchy finish.

Unthinned you can probably get away with 2 or 3 thick coats and get an even finish. If you've got 10l then you can afford to slap it on nice and thick.