This might be old news to some...but I just "discovered" Kroil.  Well, I've known about it for years with regards to being the best penetrating oil for seized fasteners.  However I only yesterday tried it on an AR15 for the purposes of removing carbon fouling.  Holy, crap.  Awesome.

So, I was cleaning up a Noveske VIS 12.5 Crusader upper, circa '09.  It is from a PD gun and has been "retired" from frontline SWAT use.  It was our Department's gun guru's upper.  He is thinking the round count is about 18-20k, semi-auto, unsuppressed.  It had also been spray-painted heavily.  Anyway, after I got most of the paint stripped off, I saw a tone of carbon fouling to the rear of the gas block.  This was a clue, as the Colt Armorer class taught me that means excess gas and possibly a leak.  After disassembly, I found that the gas tube had eroded away opposite the gas port and that was the biggest cause of the build-up.  There was basically a 2mm x 1mm "hole" that gas was escaping from.

Well, I was having a time getting the carbon off the very nice stainless barrel.  I keep a small fine-tipped squeeze bottle of Kroil with my lubricants and adhesives and decided to give it a try.  I covered the carbon build up with Kroil and let it sit for 15 minutes.  Kroil is very thin and "wet" so the excess just tends to run off and drip.  I point this out to say it was a pretty light coat, all things considered.  After sitting, I put the upper on a vice-mounted Reaction Rod (barrel still in installed in VIS upper, so very hard to get to carbon spot) and the wrapped a rag around the barrel and worked it vigorously by "sawing it" along the barrel (like you might use a wire saw to cut a branch, if that makes sense).  It took almost no work and the carbon was gone.  It had resisted Break-Free powder blast, Goo-Gone Graffiti remover, Slip 2000 spray cleaner, and a bronze brush, but the Kroil killed it.

Next I tried the bolt tail.  This upper wasn't the nastiest I've seen, and the BCG had been wiped down and oiled regularly.  However the bolt tail was pretty grungy and the carbon was hard.  I know the build-up is not a problem for function, but I wanted to get everything as clean as possible because I need to inspect the upper for damage and excess wear, as well as gauging.  The Kroil just cut through it in no time versus anything else I've ever tried.  It did take two soaks to remove it, and I did use a #1 Xacto knife on a couple of stubborn spots, but still...after 28 years of M16/M4/AR15 experience, including being an infantryman, .mil and .le armorer, cop, enthusiast, and owner of...well, way too many...my experience is that Kroil worked far better than anything else I have tried.  Smells better, too.

For perspective, I submersed the Noveske gas block in Slip 2000 carbon cutter OVERNIGHT and it took more work to scrub the fouling off of it with a bronze brush than it took to clean the barrel fouling or the bolt tail built-up.  Kroil ain't cheap, but if you have tools, work on stuff, or need to clean guns, I think it's worth the$10-13 for a can.  It's still a lot cheaper per .oz than Slip 2000 (anything they sell), Go Juice, or CLP.

BTW, for removing paint, here's the trick:

1.  Hit it with Break free in 6-inch "sections" (dries very fast) while scrubbing with a nylon USGI cleaning brush.  This breaks and softens the paint surface.  Don't try to get it all off, just scrub to disrupt.
2.  Next, get a spray can of the awesome and anodizing-safe Goo-Gone Graffiti Remover (Home Depot has it).  Soak the entire upper for 20 minutes in a heavy coat.  It will not dry up on you.  Then scrub it with a nylon brush.  I use a wheel-cleaning brush because it has bristles that are stiff but long enough to get the job done.  Wipe it down, and detail scrub missed spots or heavy areas.  This should have removed most of the paint.
3.  Scrub with hot water and an aluminum-safe cleaner.  I use the Slip 2000 pink stuff, from the gallon jug diluted per the instructions.  Make sure the water is HOT and scrub until the upper is clean of oil and the sludge.  The upper will have that just-washed look and smell, and the metal will look "dry" and slightly chalky.  Let it dry.
4a. If satisfied, I recommend soaking in Strike Hold overnight then cleaning and lubricating it as normal.
4b. If there is still paint and scuzz, you can detail clean as needed.  If there are still nooks and crannies or heavy areas that need cleaned, then go to #5.
5.  Re-cover in the Goo-Gone, wrap in plastic, and soak overnight.
6.  Go to carwash and pressure clean with wand.  Follow with spray cleaner and wash again.  This will finish it.
7.  Refer to 4a above.

Anyway, It wasn't all that hard and there is no trace of paint on this upper.  It is fully black, no damage to anodizing or the laser engraving on the VIS rail and upper.  It oiled up nicely and the whole shebang looks almost new.  I'll have to gauge it to find out how bad the wear is, and I need to get a VIS wrench to pull the barrel so I can check the gas port.  I expect it is probably fine.  The shooter was prolific, but not abusive.  He seldom ran it hard, just often.  It had been through an EAG class, three VTAC classes, and numerous SWAT training sessions.  If it is still GTG and shooting accurately, I'm going to run it on my patrol rifle for a bit.

Thanks for this write up. I have a can of Kroil but never think to use it. It was recommended to me by an older gentleman for cleaning so I bought some. I always reach for the Hoppe's. Some habits die hard.

I never heard of Strike Hold but Googled it. It looks interesting. Do you use it to lube your guns or just as a conditioner?

I have always passed on the spray painted stuff but next time I see something I want I might try your technique. Thanks again!

Nice write up. Kano Kroil is the best stuff I use at work and home, daily. It's actually better than PB Blaster and falls under 2nd place,  homemade ATF/acetone mix being the best(based on several posted online comparisons on penetrating lubricants). Says right on the can it's good for guns.

Trouble is it is not easily obtainable to everyone and is geared towards the industrial market. Banned from CA.

Don't be afraid of the paint.  Think of it as a solid film lubricant on the outside.  If an item was painted early, it is probably pretty mint under the paint layer.

Strike Hold...I keep it around because it is great on electronics...like cleaning terminals, connectors, bulb sockets; etc., and crosses over in to guns and tools well.  Iraqveteren8888 did a video on his preferred lubes and covered it, so that's why I grabbed some.  Not cheap, smells like toxic death.  But a good metal conditioner.  Since I really stripped the base metal of oil, strike hold soaks in very good and help prevent rust.  I find it soaks in much, mush faster than "normal" gun oils and once it does, doesn't seem to bother  subsequent lubricants.

I buy Kroil from Amazon.

Everything is banned in CA.

Aircraft Stripper for paint removal on metal.

You're welcome....

As an offshore instrument tech on drilling, production, and pipeline platforms, I can tell you we go through a ton of the stuff. Corrosion on valves parts is a big problem out here and we learn how to deal with it well. It works. 

I signed up with Kano, every few months they send me a flyer with an offer for BOGO, if it's Kroil or Silikroil I call and order, it's pretty reasonably priced if you do it that way.

As a Compressor Mechanic working offshore, I 2nd that.

Well driller and pump installer here. Use a ton of kroil in my shop. Funny how I forget to use it around guns.

Yeah, me too, and we get Kroil, CRC Brakleen, and Lectrakleen by the case!

Love the stuff.  Along with a copper or bronze brush/scouring pad, it works very well to remove rust from old guns.

Nice write up.

Been using Kroil n the aviation industry for many years.
It works extremely well, love the stuff

As a Qmed oiler on a 265 class liftboat I could not imagine working with out it.  Salt water corrosion is a pain.

I learned from benchrest and precision shooters to mix it 50-50 with Shooter's Choice, or 1/3 each of Shooter's, Kroil, and mineral spirits in a squeeze bottle for general cleaning.  Magic stuff.

I use 50/50  Kroil  Hoppe's mix

I've been a Kroil user for a long time. I love the stuff. It let me down for the first time a couple of weeks ago. I had a GM-22 suppressor that I couldn't get to come apart. (I know...surprised right? ) I soaked it in Kroil for a solid week, but it still didn't budge.

Will also remove rust if need be. Just let it soak a day or two.

It's my go-to when I'm sharpening knives.

Kroil stinks like cat piss and doesn't work as well as ATF/acetone.

Well DANG!! Kroil had two 13oz cans available for less than 20 bucks shipped earlier today - time ran out - I have used 50/50 of atf and acetone on  old cars and commercial equipment  with great success - add an ounce of Marvel mystery Oil and it smells great due to wintergreen oil  - Final Tip Go To a beauty supply store to get some Dye application bottles - long thin spout works great - 6 oz will last a long long time -

Kroil is all I use as a cleaning and penetrating oil. I have plenty of it at work and at home. I like the smell of it as well. It is also non flammable, so I am not concerned about spraying it on turbine engine bolts that are 1400 plus degrees.

When I get severe leading, I usually do a kroil cleaning. It works fairly well.

I am an engineer working in the refining industry and our machinist use this stuff by the cases...ride around the refinery enough and you will find a years supply of Kroil cans that have fallen off of trucks and scooters.  

This stuff works wonders, but I have never used it for guns, not sure why.  My go to spray is Safari Charlie's, made here in Louisiana, smells great and works for me.

77

Just received my first can, ordered from Amazon, yesterday.  I'm a Kroil virgin, but based on recommendations here I bought it for a brake line replacement project on a Suburban I've been reluctant to dive into.

I'm really hoping it's as good as everyone here says.  

It doesn't smell that bad; kind of citrusy.  But a little will smell a long way.

I keep 2 gallons on hand always. I wish Kano would improve the pour-ability of the damn can though.

Another piece of Oilfield Trash here;

Kroil is where it's at.  WD-40 is for poor people.

Tried to remove an LMT front sight buffer to install a Geissele Mk14 rail and nothing would work.

Soaked the straight pins in kroil and pounded those things out. It's great stuff.

Kroil + JB Bore Paste + bore patches & brush = a clean gun bore

I just this combo to clean my 10/22 rifle barrels.  Good stuff.

Yep.

I read about this recipe years ago from a bench rest website when I was learning about breaking in barrels.

Works great.

Kroil is great stuff.

My armoring instructor calls it an "armorers grade" cleaner as it can mess up various finishes if not used with some care.
BTW I been tring to find it in the needle applicator or from a place that wont double its costs via shipping.

Anyone have any good leads?

Another aircraft mechanic checking in.

We use AeroKroil by the case. Mainly for breaking frozen fasteners free.

Love the smell - it smells like what I imagine a 1930s aircraft engine assembly shop would smell like.

I plan on cleaning my Mini 30 today. It's 10 years old and has never received a thorough barrel cleaning, so, I think I'll let some Kroil sit in the barrel for a while.

Have you tried buying a separate needle applicator and just putting kroil in it?

We use a lot of it at work, recently tried it on a old Mauser that had really bad rust and copper build up in the barrel. Nothing worked. Tried hoppes and a handful of other cleaners. The kroil cleaned in minutes. Works like a champ!

Guys , sorry for the noob question but what's the difference between  kroil, silikroil,  and aerokroil,  and how do the three apply to firearms use??

Thanks

Kano Labs website would be the place to check, but from memory:
original formula, added silicone for lubrication reqd. jobs, kroil in an aerosol form

So much info here im going to print thos entire thread, laminate it and hang it on the walls of the shitter!

I had a small can of Kroil that I've had for a few years now.  I do use it sparingly so recently I wanted to place the rest of the Kroil in dispensing containers that would be easier to use.  When I poured out the last of the Kroil I noticed a black sludge that had settled on the bottom of the can and had separated from the clean Kroil that floated above the sludge.  Is this black sludge from the interior of the can deteriorating/corroding?  Or is Kroil a suspension liquid that you have to mix up and shake in the can?

I moly coat the bullets for my bolt guns. I use kroil and J-B after cleaning the copper out. This method removes all of the moly and restores the lands and grooves back to like new condition.

You can buy it straight from the company. I bought a large aerosol can for less than what I found on Amazon. You have to fill out a form online. There is a blank that requires you to enter “your company name” I just filled in Mike’s Garage with my home address and proceeded to order.

I did the ''two for one'' deal for years with the company, I have 8 giant size cans of both Kroil and SiliKroil put back now as Dad died and I always gave him the other can. Came out to somewhere like 16 bucks for two 18? oz cans.

It's great stuff. I use it for everything.

NAPA carries kroil (aerokroil) in the spray can.  Works excellent!

If you think Kroil is great on hard carbon, wait til you try their 'Kreen' internal engine cleaner. If you get this, be very careful to not get it on any furniture, paint, floors, whatever - it is very strong. The stuff is designed to be administered through spark plug holes and creep down into the piston rings, softening carbon and releasing the rings to expand as they should and seal up the cylinder again. I have used gallons of it on old coked-up engines over the last 40 years. It simply attacks carbon and dissolves it. Also their 'Flo-way' external engine cleaner is absolutely the best.