really rusty underside

[GunsMadeAmericaFree]

Just bought a manual transmission 2007 Ford Focus for $700. I put in 20,000 mile synthetic motor oil, a 20,000 mile synthetic oil filter, and new platinum spark plugs. Former owner said thermostat was stuck open, so that will arrive tomorrow. He also said that front left bearing was out, so I have 2 new knuckle/bearing sets coming to install on both sides on the front. That should get rid of the noise from the worn bearings.

Overall, seems to start, run and drive well. However, there is QUITE a bit of rust on the underside.

I am tempted to take some used motor oil, put it in my garden sprayer, and coat the bottom of it. Or, I could get some underside rustproofing spray and spray it on.

In your opinion, what's the best way to treat the underside of an old 'bottom rustbucket', to make sure it doesn't keep rusting?

Thanks!

 

[deadlyapp]

I'd first try to knock off as much of the rust as you can with a wire wheel on a grinder or drill before coating it, otherwise it will continue. You can get Por that is roll on also I think which is what I would do. I would absolutely not just oil the underside, you'll just collect more shit and probably increase the rusting.

 

[GunsMadeAmericaFree]

?? What is Por that is roll on

 

[KeithP]

?? What is Por that is roll on

Por Rust Preventive Coating

-kp

 

[GunsMadeAmericaFree]

Oh, that's the brand name! I thought it was a typo or something. I like the different colors, but man - $212 a gallon!

I wonder if it would be a lot more effective than just using a bunch of old oil based primer and several coats of oil based paint?

 

[RLGL]

Don't mess with it at this stage, you will do more harm than good.

 

[ISAslot]

Fluid Film FTW

 

[GunsMadeAmericaFree]

Fluid Film FTW

Hmm. That's waxy/greasy stuff from sheep's wool. That would be similar to taking a tube of grease and spreading it all over the bottom of the vehicle.

 

[herm0016]

I use fluid film as well, it works. I use it on an 100 year old cast iron stove we use in the summer on the patio. spray it down when done using it and even sitting all winter with a cover, it does not have much surface rust.
a rust converting primer would be good, then fluid film everything after some dry days.

 

[mindless1]

Cheap way is rather than oil, mix gasoline with paraffin or tacky grease, only thin enough for your preferred application method, then leave the vehicle outside to dry including not driving it for a day. Brush on what you can, then use the garden sprayer with a thinner mix for the hard to reach areas. I would not use this in door/liftgate panels or anywhere else, where the fumes will get into the passenger compartment.

 

[GunsMadeAmericaFree]

I'm curious - how is the paraffin better than using, for example, Diesel mixed with some used motor oil? Is it the fact that it can harden?

 

[mindless1]

^ What purpose would the diesel have? It evaporates far too slowly, most of the coating would drip off and end up a very thin application, that after picking up road muck, leaves bare metal behind soon enough. You'd be better off with a thicker oil, thinned with gasoline to reach same sprayable viscosity, or better still, grease mixed with gasoline.

Yes harder is better, so long as not so hard that it flakes off in clumps... paraffin isn't all that hard in the grand scheme of things.

Considering your username, I'd have though that you have heard of cosmoline... this is essentially what you're aiming for.

Certainly there are also, purpose made retail products... nothing wrong with them but they seem pricey for a $700 beater.

 

[thedarkwolf]

Either go with por 15 or one of the other rust encapsulators which can be a lot of work or just leave it alone. It is a $700 beater. Drive it till it is unsafe and then dump it at a junkyard.

 

[Scarpozzi]

What about that rust converter spray?

10.25 oz. Rust Reformer Spray Paint

Amazing deals on this 10.25Oz Rustoleum Rust Reformer Spray Paint at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[mindless1]

^ Works best on mild surface rust, and still needs something applied over it.

Seems like he doesn't really want to pull parts off and do a massive descaling to prep for it, and I can't blame him on a $700 car.

If not doing that, I still think something that starts thin with a carrier that evaporates away is the best bet, that continues to creep for a while while paint doesn't creep all that much after the first few minutes. If it doesn't get in behind the scale completely, it could even hold more water in, longer.

 

[GunsMadeAmericaFree]

^ Works best on mild surface rust, and still needs something applied over it.

Seems like he doesn't really want to pull parts off and do a massive descaling to prep for it, and I can't blame him on a $700 car.

You're not kidding. You should see the pile of rust flakes that came off when he was beating the knuckle to get the old bearing off of the front left. I'm half afraid that if I did much under there, we'd end up with things that wouldn't go back together.

I'm still going back and forth between the free route - using some used motor oil, spraying it twice this summer and letting it penetrate, or using something like Woolwax.

Right now, my son is replacing the thermostat, which the previous owner confirmed was stuck open. One of the 3 bolts had rusted through, and broke off. He had to remove the power steering reservoir, and go in from the side with a pair of vice-grips to get that broken bolt out of there. Thankfully, he was successful, and now he'll be able to put the replacement thermostat on there.

While it was off, we also flushed the coolant using a coolant flush kit. Other than also replacing the front left bearing/knuckle, that's all we will be doing for the $700 Ford Focus. According to the digital readout, it got nearly 38 mpg on the hour long drive up here, and that was before replacing the bearing. With both of the front bearings replaced with new, that might jump up a little bit.

 

[Torn Mind]

Trying to save such a car seems like a work of futility. It's a Ford. I wouldn't be surprised if a few more things break in due time.

I mean theoretically, rust can be stopped with phosphoric acid. But spraying a dust ridden, nasty underside of a vehicle with 15 years of "experience"....won't do much. Plus, the acid could mess other things up.

 

[mindless1]

^ Never give up. My oldest vehicle is a 25 y/o Ford, but it has a frame... so yeah, it's not about to collapse in the middle. I've had unibody cars that went to a junkyard in less time due to rust in the same environment.

You really can slow down rust a lot with a spray that creeps in enough, but getting under there, or putting it on a lift for better access, it's up to the owner how much to bother vs how much the true vehicle utility/value is to them. It might only cost $700 but my crystal ball can't tell how long till it needs non-rust-related repairs that put it in the grave.

In particular I'd want to put *something* on the strut tower mounts, and the engine subframe mounts. Things that bolt on like brake lines, are no less important, but if it bolts on... it bolts off and on again too.