I've been reading the threads going on about people having problems with rust coming from beneath the paint on their rear hatches. While this may be a very real problem for some trucks, their posts have caused other owners to claim foul with Nissan for surface contaminants which are beyond Nissans control:
That being surface rust coming from rail dust, brake dust and metallic contaminants on the back of Xterras.
This is most commonly showing up as tiny black or dark rust color marks on the paint. It's common to Xterras and probably most SUV's with poor air flow on the rear of their hatches (see picture below).
After giving my truck a thorough cleaning (yeah, it happens every once and a while), I noticed that I had developed the same spots over this winter. Realizing this is going to be an ongoing issue I decided to take care of it myself.
Any automotive shop with a decent amount of car cleaners should have detailing clay bars. Mothers car care has one, but it goes for about $24. For now I decided to buy Meguires newest addition that includes a clay bar and detailing solution for $9.
Removing the spots is very easy. With a clean paint surface you use the detailing spray to lubricate the surface. Then run the bar over the spots until they disappear. It's pretty much like having a pencil eraser for your paint. I was actually amazed at how much surface dirt came off also. Within less than 10 minutes I had removed all the spots and a long standing stain that I had not been able to buff out when waxing.
Owners should really consider having a clay bar around for cleaning their trucks. If you don't take care of it now the rust can eventually cause damage that won't be so easy to remove.
The other area I was going to mention is under the fender flares. Most offroaders notice that the rear wheel well flares catch tons of mud and dirt. If you resist the temptation to keep the mud on until next Monday to show off to your co-workers, it's pretty easy to get off in a spray-n-wash on the way back from offroading.
I decided to check the front flares, which don't have the extra lip that catches so much dirt on the rear.
Yup. More dirt and mud had worked its way under there too. I also noticed that the same rust specs described above had begun to form.
So if you're cleaning your truck up this spring, make sure you pull the flares off, and clean everything up. A extra coat of wax on the paint underneath couldn't hurt things.