I've a 2015 Jeep Grand Cherokee Limited. My wife has a 2014 Chevy Equinox. Being in Michigan, road salt is the grim reaper of cars and trucks.

Talking to the place that's going to detail our vehicles, a woman recommended we also get them treated for corrosion protection by a place called Krown Rust Control.

Unlike traditional undercoating, Krown's process is to spray the underbody, wheel wells, engine compartment (selectively), panel interiors (doors, tailgates, rocker panels, etc.) with a penetrating oil.

They recommend re-treatment annually, since it's an oil, rather than a permanent coating.

Questions:

Does anybody know if modern vehicles even need corrosion prevention treatment any longer?

Has anybody here had any experience with Krown?

I do not have any personal experience with Krown. But I have always treated the undersides of our vehicles in the fall with Fluid Film. I’m sure it’s much more cost effective and only takes a half hour or so.

I remember seeing this on some auto tv show, the oil based coatings were touted as being very good, lots of articles on the innerwebs.

NH Oil was the one they talked about, I think, maybe, probably....

https://nhoilundercoating.com/...vs-oil-undercoating/

https://nhoilundercoating.com/...rust-proofing-spray/

Fluid Film seems to be popular throughout some 4 runner forums I read

Krown is good to go!! I wish I had one closer. They do a great job and do more than just the under carriage. They get in rockers and door panels where they can.
$150 I last checked for a large SUV is a deal.

A fluid film DIY kit is $150 (with gun) and the fluid film itself is $75 after that.
Well worth the $75 in labor to be done on a lift.
October/November is the best time to do it or before winter really hits in your area.

Fluid Film is good but smells pretty strong.
WoolWax is really good as well and does not stink.

Local off road shop uses the Woolwax here and also charges $150.

If you are anywhere that uses road salt or even worse the salt brine solution it is an absolute must!

Thanks for the comments, everybody. At this point I'm thinking we'll keep the appointments I made earlier today and get it done.

quote:

Originally posted by ensigmatic:
Thanks for the comments, everybody. At this point I'm thinking we'll keep the appointments I made earlier today and get it done.

I would not get it done until later in the year. It does come off.
You generally want to apply it late fall that way it is still on heavy for the harsh winter months.
Spring and summer rains will wash a lot of it off and you won’t have nearly as much protection as doing it later in the year.

Yeah... I'd had that at the back of my mind. Maybe I'll do just that. Thanks for the tip.

I have had very good success with chain saw bar oil diluted with kerosene so that it will be able to spray through a gun. It makes a bit of a mess at first application, but then forms a very protective film that lasts a few years. Probably very similar to what you have scheduled to have done.

I don't think Jerry Lundegaard is a member here, but he'd recommend the Tru-Koat.

quote:

Originally posted by architect:
I don't think Jerry Lundegaard is a member here, but he'd recommend the Tru-Koat.

yes you're definitely gonna want that Tru-Coat

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I use Krown in spray cans every year on my trucks. I just put it up on a lift and spray the entire undercarriage electrical connections and all. It DEFINITELY slows down the rust significantly IMO. Have some similar aged vehicles I compare to and the ones getting treated with Krown have way less rust.

Thanks for the additional comments, everybody.

Krown does appear to be the Real Deal. I cancelled the appointments for tomorrow and set a calendar date to remind myself in September.

Update

When I informed the local Krown guy of my decision to hold off until late summer, early fall, he asked why. I told him. His response, in part:

quote:

Got it. I guess I've seen it in action a year later... last week, for example, and perfect condition. [But whatever] you're most comfortable with.

So perhaps it's a bit more long-lived than that for which some give it credit?

quote:

Originally posted by ensigmatic:
Update

When I informed the local Krown guy of my decision to hold off until late summer, early fall, he asked why. I told him. His response, in part:

quote:

Got it. I guess I've seen it in action a year later... last week, for example, and perfect condition. [But whatever] you're most comfortable with.

So perhaps it's a bit more long-lived than that for which some give it credit?

I was not saying it won’t be there but it will be diminished compared to the original application.
I just think it is best to have it applied right before one will be in the most harsh period and want the maximum protection.

Kind of like buying an Iced tea 20 minutes before you plan to drink it.
Sure it is still tea and drinkable but it will also be watered down and not as good. (I type this as I sip on tea I bought at 0745 this morning).

We get lots of rain here in the spring and fall plus I go off-roading so I power wash the underside a few times during those months. I want as much protection as I can get for the winter.

I promise if you ask him for a break down of how many applications he does by month (if he is willing to share) you will see a large difference between April and November.

quote:

Originally posted by Black92LX:
I was not saying it won’t be there but it will be diminished compared to the original application.
I just think it is best to have it applied right before one will be in the most harsh period and want the maximum protection.

I understood that and, as I'd noted, had already been thinking along those lines, anyway. Your suggesting mainly just nudged me over the edge

On a low mileage 2013 GMC truck does Krown clean the underside before applying their product? If so doesn't it have to thoroughly dry before application of the product?

I rely on my leaking tranny to provide a constant supply of atf to keep my trucks underside treated, as well as the street in front of my house.

Break Free CLP? Just get a large drum of it.

Seriously I don't use any additional undercoating or rustproofing because the spray on stuff that solidifies can cause bigger problems. GM had issues with vibration at highway speeds on Blazers that no one could figure out. Wheels, tires, brakes, etc. Turned out it was undercoating sprayed onto one side of the drive shaft that caused an imbalance. Former boss had a fender rust out from the inside because the rust proofing plugged all the drain holes and it filled up with salty water from snow in the winter.

So anything oil based that leaves a film but no thickness of material would be a good idea. Rust preventatives used in shipping of industrial products such as BioCorr or Castrol Rustilo might work too, and probably cheaper than anything marketed for the specific purpose of undercoating vehicles.

quote:

Originally posted by ensigmatic:
Update

When I informed the local Krown guy of my decision to hold off until late summer, early fall, he asked why. I told him. His response, in part:

quote:

Got it. I guess I've seen it in action a year later... last week, for example, and perfect condition. [But whatever] you're most comfortable with.

So perhaps it's a bit more long-lived than that for which some give it credit?

Why wait, one could also suggest that with nicer weather, it's not snowing it might be a good time to get it coated,

I just don't see the product deteriorating between April and October. Either it lasts a year or it doesn't and if you want the car protected, hit it now, let it start working it's way in, protect from the humidity and rainy weather during the summer, and then hit it again before winter if you think it's necessary.

They have FAQ's on Krowns web page, of course they tell you to get it done now and that it doesn't make a difference, maybe it doesn't.

https://www.krown.com/en/faq/