Frame Rust Control - How Did You Do It?

[TumblrDucks]

Thread 'Is this too much rust for a GMT360 Truck?'

Apr 4, 2025

Recently fell in love with Saab 9-7x, it uses the same platform as Trailblazer, Envoy, Rainer, etc.
Pics below are sent by a private seller I'm in touch with. I have no experience with GM and framed SUV, how does this rust looking for a 2009 vehicle in Ohio? Acceptable or I should walk away?

• TumblrDucks
• Replies: 10
• Forum: Mechanical/Maintenance Forum

Well, I got my Saab 9-7x, a GMT360 based vehicle.
The frame got some flavor - mostly looks like surface rust, one spot around the frame under the engine has more rust, but the frame is still holding. Rear trailer arm brackets are start getting crusty, but so far the trailer arm still holding without issue.

So how would you stop the rust in track and prevent further degradation? I heard Eastwood product are good, so I did some resarch. It seems like Rust converter + Rust Encapsulator should be a good combo to stable current rust and stop future rust, but what about frame interior? And do I need to paint over the frame after I encapsulating the exterior?

Open to your suggestions!

 

[MurkyAsparagus]

The converter is a good idea. I know many, including myself, who do annual or biannual fluid film / Krown (retailer) applications. I use fluid film on just about everything - mowers, electrical connectors, cars, jetskis, boats. Pretty much anything I don’t want degrading gets fluid filmed.

 

[CDX825]

If you are going to drive it in the winter then do woolwax or fluid film.

 

[Danno]

Krown, annually.

 

[Wrenchturner44]

I would use Eastwood Rust Converter first. Make sure you can get inside the frame too if possible. Then use one of the other topical products mentioned above.....Fluid Film, Krown, or woolwax product.

 

[JTK]

That would be miraculous if the little bit we can see from the pics is the worst of it on a GM T360 chassis. I know you said the rear trailing arms are good, but what about the frame wheel arch and the front attachment points for the trailing arms? The rust I see in the pics could be slowed down some with oil/wax based products once you get the loose flaky stuff off first, but you're going to have to keep these areas gooped up all the time.

Here's a great video of the classic GM T360 rust issues..

 

[Fattylocks]

Moved 500 miles south from Chicago.

 

[TumblrDucks]

That would be miraculous if the little bit we can see from the pics is the worst of it on a GM T360 chassis. I know you said the rear trailing arms are good, but what about the frame wheel arch and the front attachment points for the trailing arms? The rust I see in the pics could be slowed down some with oil/wax based products once you get the loose flaky stuff off first, but you're going to have to keep these areas gooped up all the time.

Here's a great video of the classic GM T360 rust issues..

Thanks. Yes, the attachment point on driver side is concerning- it still holds the arm in place when driving, but the metal around bolt hole start caving in if I press it hard. I would like to stop rust on both attachment points to avoid a welding job.
Needs to check wheel arch once I got it on jack stand

 

[TumblrDucks]

I would use Eastwood Rust Converter first. Make sure you can get inside the frame too if possible. Then use one of the other topical products mentioned above.....Fluid Film, Krown, or woolwax product.

Got it. Would 1-2 quarts of rust converter enough to be brushed over the entire frame? I will try using converter spray for frame cavities as well.

 

[Wrenchturner44]

Got it. Would 1-2 quarts of rust converter enough to be brushed over the entire frame? I will try using converter spray for frame cavities as well.

I not sure 2 quarts would be enough. I think if the frame has any pitting at all may want to coat each of those areas twice.

 

[hardcore302]

I remember reading a story on here about an older man with an older car that informed an admiring inquiring passerby that he used the old oil from oil changes and put it in a sprayer to coat the undercarriage.

 

[wings&wheels]

We plan to take the Jeep JL on the beach this year so I'm planning on ding the DiY Waxoyl interior fogging oil and hardwax application after the clutch recall is done. This is a '21 and never seen winter's salty roads but already has some surface rust on frame edges, welds, etc.

 

[TumblrDucks]

That would be miraculous if the little bit we can see from the pics is the worst of it on a GM T360 chassis. I know you said the rear trailing arms are good, but what about the frame wheel arch and the front attachment points for the trailing arms? The rust I see in the pics could be slowed down some with oil/wax based products once you get the loose flaky stuff off first, but you're going to have to keep these areas gooped up all the time.

Here's a great video of the classic GM T360 rust issues..

I was able to get some photo between the rains this afternoon.

I paid attention to pic 3 and 4. Pic 3 is passenger side rear trailing arm mount. Pic4 is driver side with worse condition.

 

[nascarnation]

I like Woolwax a lot. You have to respray every couple years but it's easy on your hands when you work on stuff and it smells nice in a non-petroleum way. Being lanolin based it's nicely compatible with various elastomers on the underside. The sprayer they sell works really well and because the stuff doesn't harden up you don't even have to clean the gun afterwards leaving it ready for the next application.
Do your crack/corrosion repairs first of course. Nobody is gonna look at those welds so you don't have to be shy about any lack of quality with your MIG beads.

 

[webfors]

Krown annually and buying a 12 pack case of their spray. Every time the cars are on the lift, and before and after winter, I spray all the sensitive spots and underneath. Heavy on the spraying until all that orange is saturated, then maintenance.

 

[TumblrDucks]

I like Woolwax a lot. You have to respray every couple years but it's easy on your hands when you work on stuff and it smells nice in a non-petroleum way. Being lanolin based it's nicely compatible with various elastomers on the underside. The sprayer they sell works really well and because the stuff doesn't harden up you don't even have to clean the gun afterwards leaving it ready for the next application.
Do your crack/corrosion repairs first of course. Nobody is gonna look at those welds so you don't have to be shy about any lack of quality with your MIG beads.

Thanks. How did you start your welding journey?

 

[mattd]

Noxudol 300/700

 

[nascarnation]

Thanks. How did you start your welding journey?

When I retired, I did a restoration on a 67 Camaro. I bought a Hobart MIG welder, watched some videos on YouTube, and had fun with it. To be a good welder it helps to have good close up eyesight and a steady hand. I don't have either one LOL. I also recommend getting a welding helmet with a big viewing port, they are cheap these days.
You'll also become a hero to your neighbors when they need some small jobs done.
Good luck.

 

[jsean]

I was able to get some photo between the rains this afternoon.
View attachment 277491View attachment 277492View attachment 277493View attachment 277494View attachment 277495View attachment 277496View attachment 277497View attachment 277498

I paid attention to pic 3 and 4. Pic 3 is passenger side rear trailing arm mount. Pic4 is driver side with worse condition.

It’s a salt belt vehicle, so it’s what it is. The SAAB 9-7xs were always cool I thought even thought they were just rebadged Trailblazers.

IMO, your first step should be to take a screw driver and verify that everything is truly surface rust.

If it is and you plan on keeping this 9-7 a long time, I’d suggest that you clean up the frame and other rusty parts, wash it down, apply some rust prep after it’s all dried up, clean off any excess and then apply a good rust encapsulator (I like POR15 but there are other brands out there).
Once that’s all done and good to go, spray the inside of your frame yearly with fluidfilm and coat the underside with blaster surface shield. Good luck.

 

[PF52]

I use Surface Shield..... Similar to Woolwax and Fluid Film. Yes, it has an interesting smell, kind of like a barnyard. Get the flexible applicator to be sure to get the stuff inside any holes or openings in the frame.