This is informational, because I see a new YouTube going around about using Drano to clean out clogged sunroof drains. This seems to pop up every few years, but consider this before you try it: Many times leaks in older cars are caused by shrinkage of the drain tube material, causing the tube to detach from either the top or bottom nipple. Pour Drano into a detached tube and either your headliner or carpet will go up in a puff of Drano steam. Expensive and unpleasant at the very least! Drains can also kink where they make a sharp bend, older Altimas are famous for it at the lower front fittings. Pour Drano into a kinked tube and not only won't it work, but you'll be donning sewer-gloves to remove the old tube without burning yourself or anything else.
So, if it is a clog and not a detachment or kink, what to use? Stubborn clogs that won't blow clear are usually a combination of mud and tree sap accumulated over time. Occasionally mud wasps will nest in a tube if the roof is frequently open in a garage, so you may have mud and wasp-spit instead of sap. Bug-splat remover works well to loosen both of these, and it won't take the paint off the insides of your fenderwells. If that doesn't work, bite the bullet and remove whatever you need in order to inspect the hose. Drano is for toilets and it works fine, but your car shouldn't be treated like one.
AZ, I wasn't sure where the right place was for this post, please relocate if needed.
