WD-40 does a great job of cleaning lots of things, such as stainless steel and inkjet printer cartridges. But if you're dealing with a particularly dirty toilet, and nothing else seems to be working, a little WD-40 in the water may be all you need to break down those stains.
Update: It's been brought to our attention that spraying WD-40, which contains 50 per cent mineral spirits, into your toilet and flushing it is not ecologically sound. As such, we can't recommend following the advice provided in this post from the US site. Thanks to everyone who made us aware of the issue.
The key here is to only use a small amount -- there's no need to go spraying down the inside of your toilet just to get rid of the lime stains and discolourations left behind by the last person that lived in the apartment you're now renting. Give it a squirt or two, a few minutes to break up, and then attack it with a toilet brush. Follow up later with bleach, vinegar or whatever cleaner you prefer.
I can vouch for this one working as described, but it should be a last resort. WD-40 is still a commercial chemical with a specific purpose (and hundreds more off-label uses) and should be handled with care. Do you have any other ingenious WD-40 off-label uses? Share them in the comments below.
13 Amazing Uses for WD-40: Clean Toilet Bowls [Reader's Digest]