I respectfully disagree on the use of Kroil. It is OK for fasteners that are not really all that stuck, but in my experience, it has frequently failed to penetrate more than a couple threads deep on many screws that were not severely rusted. This has happened to me with Kroil many times even with repeated soakings over extended periods. There are much better alternatives out there in my opinion. I've had some successes with pure Oil of Wintergreen recently. I've been trying Burlite which is sold by W. E. Boyd who often posts here under the name of Docbill. It seems very good, but I haven't used it enough to give an honest glowing endorsement. A 50-50 mix of acetone and ATF works well, but it needs to be reapplied often for severely stuck screws because the acetone evaporates quickly. I do like Zep 45 and had good results with it in a very corrosive environment. I still have not tried Mouse Milk. Many guys on antique tractor forums swear by it. Has anyone here used it?
Obviously, this is an area of interest to me as I do a lot of work on old firearms and old farm tractors, etc. I've used literally dozens of brands and concoctions in a vain attempt to find a replacement for Cabot's Tasgon which was discontinued in the early 1980's due to it's creosote content. I have a small amount left which I only use when everything else fails. If you can find a partial can at a garage sale or flea market, buy it. It has worked on many things that appeared beyond hope. Even Tasgon will not help once galling has occurred, so I always preach patience and repeated, extended soakings along with applications of heat, cold, and shock to facilitate penetration. Some screws that surely would have been twisted off with agressive early attempts have broke free easily after several months of occasional application of a good penetrating oil. I have perhaps 2 gallons of Kroil in my shop. I continue to use it as a penetrant when it looks like a fastener is not severely stuck. I also use it on 0000 steel wool to remove rust on guns. But even there, WD-40 works better. All penetrating oils are fantastic when they work. And I know many feel Kroil is great. I just don't think it's much better than plain old kerosene. I'm basing my comments here on decades of what has and hasn't worked and literally thousands of applications.
Dittos on the use of quality gunsmithing screwdrivers. Just as important is the guy behind the screwdriver who knows how to use it and when to back off before doing real damage.
