Worried Anti Roll Bar securing bolts may be difficult to undo? Advice

[Submariner1]

I am worried the 4 bolts holding the antiroll bar bush might have corroded, and be difficult to remove.

On 2 of the bolts, I can get to the exposed end of the bolt, and hence have sprayed penetrating oil on them for a few days. The other 2 go into a box section. So I can’t spray the end of the bolt, only the head
If any of the threads attached to the subframe sheared it would be a nightmare … very limited access.

Q: Is it better to use my 3/8” drive (air driven) impact gun, starting slowly at low pressure/torque. Or a spanner? Which is gentler? i.e. less likely to shear off.
A Class is 2002 so 22 years old, on 72,000 miles.

reason for concern:
All the bolts on the suspension parts came undone nicely except one.
The bolt securing the Top Suspension mount-bearing block to the body sheared off see photo
It seemed tight on a 3/8” rachet so I used my long wheel brace circa 900m bar. It seemed to move then sheared off.
Luckily the mounting block was to be replaced as the bearing was knackered.

kinda shocked the steel bolt sheared going into aluminium? I thought the aluminium thread would have given first.

 

[Oldspanners]

On my C class W203 I had the same sort of feeling. I used a mixture of 50/50 old ATF and acetone to soak all around the bolts for several days before attempting to move them. They will be extremely tight due to the different metals and I used a 3/8 drive socket and very slowly worked it back and forward. Any sort of power tool I would avoid due to the lack of feel but may be useful on a very low setting just to vibrate. If it feels too tight it will shear, so apply more penetrating fluid and try later. It took me about 30 minutes to remove one particular one but that's better than the other option! Patience was never my best trait but in this case it's a necessity.

 

[JoeHorner]

Just did them on our 2003 (likely for the first time looking at them) and they undid without a problem using a 3/8 ratchet handle to crack them off then 3/8 electric ratchet to spin them out.

The drop-link nuts, on the other hand, I had to cut off and ended up replacing the inner track rod on one side in order to do the outer because there was NO way the adjusting nut would ever undo again. So it's not exactly a rust-free car around there!

 

[Submariner1]

How many miles on your car?

 

[JoeHorner]

How many miles on your car?

On ours? About 135k.

But no sign of them ever being done in the (incomplete but lots of) history that came with it or on previous MOT fails / advisories.

 

[Jason63]

In my experience an impact wrench shears bolts a lot less often than a breaker bar. The hammering action is much more likely to break it free.