So I recently in the last 5 weeks purchased a 2006 ford f-150 fx4 from CarMax it has 119,000 Miles it is in perfect condition not one scratch on the paint all the leather and interior is like new it was almost to good to be true for the price after I purchased it I put some after market parts as I was working on it I noticed A LOT of rust under the hood and under carriage I took it back to CarMax and they replaces the rear differential covers and a few other things due to the rust flaking really bad and they assured me the rest was just surface rust I just want to see what others people who know about rust what your input is I don't want to pay for something that is going to fall apart in 6 months I did get the 150,000 mile warranty

 

Any advice ??

 

I have some surface rust on mine, nothing too bad and i havent had any issues.

Check the bottoms of the doors and the wheel wells. If its going to have a rust issue its going to be in those two places. the rest of the truck is pretty solid.

Edit: I cant see your pictures since my work server blocks them so I cant compare what my truck has to yours.

 

The rust on the drive shaft is normal. However I would steel wool the stuff you can and then paint the spots you can. I am not a pro just telling you what I would do.

 

My worry is that it will start too get worse and stuff will fall apart

 

I just traded a really nice 2004 XLT Crew Cab that had surface rust underneath - differential, axel housing, frame tips and welds, spare tire, trailer hitch, some lower seams... None of it was close to rust through. My truck even had rust proofing. I live in an area that uses a lot of salt. I would just clean it up with WD-40. Did your vehicle come from an area where rust is expected. I would only worry if truck came from New Jersey and New York City and possibly was an Irene victim. On my new truck, I'm trying Rust Check which they use in Canada a lot.

 

The underside of every vehicle rusts. Depending on where you live some more than others. Nothing in your pictures is of any structural concern although the spare tire looks ugly. Carmax has a great reputation for NOT selling anything that has structural problems and making good on anything that was overlooked. They spend a lot of time going over the vehicle for you peace of mind.
If you want to paint what's rusty use Rustoleum rust prep first. It kills the rust and penetrates to the clean metal without you having to scrape a lot.

 

Someone on this forum wrote that wd-40 would just attract water, its defintly not that same as the oild based products rust proofing companies use.

NOT every vehicle rusts. We brought a 6 year old suv from Florida that was originally from North Carolina its had abosolutly no rust on it.

After two winters in Toronto its underside looked 3 times worse then the original posters F150. Rust will EAT your car withing a couple of years when it starts.

To the original poster the rust that you posted isn't too bad yet. But I would get some serious rust proofing done before the winter with some spray paint based stuff and in all the crevices an oil based compound. Clean prime and paint it.

Otherwise your structure WILL rust through unlike some people said here.
If you live in a warm climate with no salt and no winters then rust like that won't get worse fast enough for you to bother doing anything.

Here's mine: (again Florida truck and 2 Ontario winters here)

 

That rust is nothing to worry about climb underneath a 2012 f150 after its been through a northern winter and it would look similar underneath with the amount of rust.

 

My truck is located in sacramento ca I got it in. Modesto ca not sure where rust was from do you think I'll be okay in sacramento or should I sand it down and paint it