Disclaimer: The following is provided as a GUIDE ONLY, and neither myself nor Ozhonda take any responsibility for the outcomes of someone else doing the following. You follow these steps at your own risk!


Aim:
To replace old & worn rear tail light gaskets. I was sick of having water in my boot after just 1 day of raining.

Required:
Cutting board
Very sharp knife or very sharp stanley knife
Permanent marker
25cm x 100cm closed cell foam/rubber material (bought from Clark Rubber) @$29.99 per/sq. The minimum is half a meter, but the dude was ok with selling me only a quarter of a meter. Paid $7.50. Purchase the material that is twice as thick as the old gasket.
Very sharp scissors, small to medium sized
Your old tail light gaskets to be used as a template
Methylated spirits
Cleaning cloth
8mm socket and/or 8mm spanner
Flashlight
2 hours of free time

Steps:
1) REMOVE TAIL LIGHTS. Remove rear tail lights using 8mm socket/spanner. 4 nuts hold the tail light in.

2) STENCIL OLD GASKETS. Remove old gasket and place on top of the new gasket material (from Clark Rubber). Draw a stencil of the old gasket onto the new gasket with the permanent marker.
Step 2 - End Result.


3) CUT OUT STENCILS OF NEW GASKETS. Using the cutting board, sharp scissors and knife, carefully cut out the stencil. The best method i found was to fold the gasket in half and cut out a slit, then use the scissors to cut out the shapes. With the smaller holes, it's easier to do the same thing, but make ' V ' shaped cuts into them, then fold the other way and repeat. This gave me the best shape to seal around the bolts. With the locating holes, just use the knife and push through the material, but not too far, enough to go through. You'll want it as tight as possible around the locating studs.
Step 3 - End Result.


4) PREP TAIL LIGHT AND VEHICLE SURFACES. Clean the tail light gasket edges using the metho and a cleaning cloth. Also clean the car's tail light section with metho and a cleaning cloth. This will ensure there are no contaminents and the seal is as clean as possible.

5) FIT NEW GASKETS TO TAIL LIGHTS. Place the newly cut gasket onto the tail light, with the permanent marker side facing the tail light (no one is going to see it, but it just looks cleaner to me). The new gasket for the left side will be used on the right side and vice versa. But if having the marked side facing you doesn't bother you, then disregard.
Step 5 - End Result. (Before and After)


6) ISNTALL TAIL LIGHTS. Install tail lights with new gaskets back onto car. The fitment will be a lot tigher and will require more effort to install, as the gasket is twice as thick. I place it on there, and did all the nuts up by hand as tight as i could. Put your weight behind it and push, as you push tighting the nut. Once all were hand tight, i used an 8mm spanner to tighten them all. Up to you, but i did it in a gradual, criss-cross sequence, like you would a head gasket, extractors, etc. But if you're not fussed, disregard. This ensured a good, tight and even seal.

7) LEAK TEST. A good excuse to go to the carwash and clean your pride and joy. Wash your car as normal, but spend a bit of extra time around the boot/hatch with the rinse. Once finishing washing the car, check for leaks from INSIDE the car. DO NOT OPEN THE BOOT/HATCH, as this allows water to drip directly into the boot, giving you a false leak. I used a flashlight from inside the boot to check for leaks.
Step 7 - End Result. NO LEAKS!!!!

Other comments
I hope this helps everyone! Enjoy!