Going to do a new catback exhause sometime in the future. The bolts are rusty at 106k miles. Not too bad - I can still make out the exposed threads - but rusty nonetheless. Since I'm not ready yet, is there any benefit to spraying with Kroil, say once a week, and letting it soak? Will it help to let the penetrant go through heat cycles before I try to remove the bolts, or is this just wasted effort until I'm ready to turn the bolts?
From experience dealing with rusted bolts I can say any little bit helps so it definitely wouldn't hurt and could possibly make the whole experience much more enjoyable.
Go outside, Kroil it now. Do the work whenever.
Its so easy, who cares if it works.
My favorite exhaust wrench is a wiz wheel or sag. Slice and remove.
Kroil soaking (or PB blaster, etc) certainly won't hurt.
Kroil is the King!
I love that stuff. maybe soak it a couple times just before you do it. I don't know if heat cycles would help...
PB Blaster > Kroil
digdug18 wrote: PB Blaster > Kroil
I agree.. at least I can run down to the store and buy PB Blaster anyway.
My buddy Mike swears that he will spray AeroKroil on a rusted nut and come back 10 minutes later and the nut is sitting on the floor.
digdug18 wrote: PB Blaster > Kroil
If you were any more wrong you would be carkid. :)
As much as I like PB ^ is right on the money.
As a side note, Kroil people were running a special where you could get a can to try for shipping only. I ordered one to try and it showed up a couple of days later. About a week after that a whole case showed up with my address on the outside but some shop in CA on the invoice inside. It took them about a week to figure out what happened and since I was nice enough to give it back to them they let me keep 2 of the cans. Nice people.
someone sent me an article recently that compared all penetrating lubricants, PB Blaster , Kroil , WD-40 ..ect.
The best by FAR was a 50/50 mix of atf and acetone.
Does anyone remember the article that compared penetrants? What did they mix together that loosened bolts better than PB and Kroil? BTW, I'm in the PB camp b/c its easy to find, but I like kroil better.
Nevermind....found it.
Rusty bolts? Make your own super rust penetrant! Suggested by John Brown
So you deal with a lot of rusty nuts? Go down to the hardware store and buy some acetone, a quart of Dexron Mercon and a refillable spray bottle. In the spray bottle mix the ATF and acetone in a 1:1 mixture.
Spray away and get your nuts loose!
Independent testing of penetrating oils using a single steel bar with 1/2”x20 nuts torqued to 50 ft/lbs and treated with a 10% salt water solution that was allowed to rust. Listed are the chemicals and required removal torque.
-None ………………… 516 pounds
-WD-40 ……………… 238 pounds
-PB Blaster …………. 214 pounds
-Liquid Wrench ….. 127 pounds
-Kano Kroil ………… 106 pounds
-ATF-Acetone mix….53 pounds
AutoXR wrote: someone sent me an article recently that compared all penetrating lubricants, PB Blaster , Kroil , WD-40 ..ect. The best by FAR was a 50/50 mix of atf and acetone.
That's good grassroots info.. I can't wait to try it!
As one who has tried the atf/acetone mix, I can say it was lousy. Starting with the fact that they don't mix. So you're either applying ATF or acetone, but never both.
Kroil, I've used it for years. Vastly overrated imo.
The torch and candle method is another grassroots technique. Never have tried it. The notion is to heat up the offending fastener, then touch a candle ot it. The claim is that the wax will be wicked into the rusted threads, magically releasing it.
I love the strange names of many of the penetrating oils. Mouse Milk is one that I find especially appealing from the name.
foxtrapper wrote: I love the strange names of many of the penetrating oils. Mouse Milk is one that I find especially appealing from the name.
Mouse Milk sucks, at least in the applications I tried it on. I thought it was worse than WD40.
I know it is mainly used in aircraft stuff, so maybe it is better for bimetallic (aluminium/steel) than for rusted bolts.
I think Kroil works great. I love the stuff.
I've got a can of stuff I got from a friend - who got a case of this stuff from a factory where he used to go and fix their forklifts - called "Heater Control Valve Solvent"...or something like that.
I had to do the brakes on my 88 Chevy 1/2-ton last weekend. The left-front caliper was locked up, and I decided to do the full job of calipers/pads/pins/rotors/bearings/seals/hoses, I also discovered one of the rear hard-lines had a slight leak which turned into a geyser as soon as I touched it.
I soaked everything down with that solvent as I was taking it apart. The calipers/rotors had been changed about 6-7 years ago, so I wasn't too surprised they came free, but the hoses and hard lines are original(I know, the truck has been in the family since new), and it's primarily been used as a winter beater for the last 5-years.
I was completely amazed at how easily the hard-line/hose junction broke free, as did every rusty nut & bolt I turned.
I'm sold...now I just need to find more. 
I had to remove a rusted exhaust manifold on a 8v VW. Soaked it every day for a week with Liquid Wrench. The nuts came off so easy you'd think they were brand new!
doc_speeder wrote: I had to remove a rusted exhaust manifold on a 8v VW. Soaked it every day for a week with Liquid Wrench. The nuts came off so easy you'd think they were brand new!
I call BS. VWs are designed to have every nut drilled and retapped EVERY STINKING SERVICE 
From a physics standpoint, I don't see how the ATF/Acetone mix could reduce break-away torque of a fastener (rusted or not) to that small above a dynamic torque application.
Think about pushing a block of concrete across a parking lot. When is it the hardest to move it? When it's standing still. To have only 6% higher static friction vs. the dynamic friction being applied with a torque wrench... maybe, but I have extreme doubts.
Always willing to try something new ... I'm a PB guy and will order up some Kroil .... Do those of you that use it have the aresol "airokriol" or just the drippy stuff?
I used the "drippy stuff" 'cause it was given to me free. If I had to pay for it, I would probably go w/ that again. Airokriol probably has less liquid in the can.
Never tried Kroil but PB has never let me down. WD40 is by no means a penetrant, it's best used to lube holesaws or as a light duty cutting oil. Other than that I have not had an enormous amount of luck with it.
But in reply to the OP's original question: yes there is a benefit to several soakings, particularly when heat is involved. I'm doing that now on a Cosworth Vega so I can get those damn tube nuts for the air injection manifold out of the original header. Start the engine, run it for 2-3 minutes, shut it down and PB the tube nuts. Then a 9/16" crowfoot flare nut wrench and a lot of cussing will be used. When everything goes back together, use the copper based anti seize (the silvery stuff is worse than useless) so that if it ever does have to come back apart it actually will.
In reply to Jensenman:
WD40 works great for cleaning stuff, and flushing out grease and such.
Joey
joey48442 wrote: In reply to Jensenman: WD40 works great for cleaning stuff, and flushing out grease and such. Joey
It's a good cutting oil for machining aluminum too. Not a penetrating oil though.
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