check for good quality chemicals specific for the purpose. To prevent rusting all together, put a hard thick coating of paint. Avoid lead.
You don't. One, it is illegal. Two, It would cause a exhaust leak that if it got inside the vehicle would be poisonous to the driver and passengers.
If the drain plug under the evaporator coil is plugged up it will cause condensation to leak into the car. If the heater core is bad it will allow coolant to leak into the car. If the leak is warm and smells sweet it is the heater coil.
Your windshield gasket leaks on the top. I had the same problem when I had the roof replaced. They put the winshield back in but didnt seal it properly.
Check for a vacuum leak around the throtle body and intake manifold.
A fuel leak that you havent detected yet maybe try this I had this prob w/ my 95 Cherokee after having everything else checked out .... I replaced the gas cap, a 5$ fix, o-ring was worn and allowed fumes to leak out causing smell....hope that helps
The shower diverter is loose or broken inside and needs to be changed.
Seats in the main valve body are leaking by, allowing water to go to the shower head.
If you have a new pressurised water system there is a possibility that the added water pressure could cause a leak.
Shower body or pan not properly supported or the joint not properly caulked possibly a fiberglass pan with plastic piping
It rusted out
There are many things that can cause a shower faucet to leak. Some of the most common reasons for this are poor quality washers, washers are the wrong size,loose nuts, build up of residue on the faucet inlet.
Blown head gasket
there is a leak in the drain pan that the evaporator sits in inside your furnance
the shower and bath water comes from two different places so their is two different pipes. Get the shower pipe checked out by a plummer and they cause fix the pipe.
Gravity. Also- If someone takes a shower with the curtain on the outside of the tub this can happen.
As long as care is taken to insure that the shower liner remains inside the tub, there should be no water leakage.
Any fuel spill,storage or leak can cause fuel odor inside the car.