Freeing rusty bolts - best penetrating oil

[Captain Larry-DH]

This is an interesting test. Bottom line - when turning a rusty bolt heat is best, but when you can’t use a torch Liquid Wrench is better than the other products tested. I was disappointed by the P-Blaster results- it’s always been my choice (and I own 2 cans). Of course, there are also nut splitters when you need to free a nut (not turn a bolt).

 

[JamesG161]

I have seen similar test before.

The number one in that test = Brake Fluid.
#2 = Deep Creep by SeaFoam.

Never use Acetone.

2 more issues
1) This is Iron to Iron corrosion.
2) How about Iron to Aluminum?
3) It takes many hours and repeat applications to assure penetration of any Penetrant.

But here is the updated version

 

[RitSim]

I read a test (don't remember where) but their first pick was 50/50 acetone and transmission fluid.
Have used most of the suggestions above. Also have had to resort to a nut splitter if there is room. Otherwise I drill a hole down thru the nut parallel to the bolt and missing the threads on the bolt. Start small and enlarge as needed. Final removal is using a cold chisel.

 

[MaryEllaRose]

If it’s possible to use heat, try beeswax (not canning wax or candle wax)…pure beeswax. I was skeptical at first but I’ve become a believer.
Tom G

 

[WayneH]

I've tried WD-40 and PB Blaster and was unsatisfied with the results. I freed up a set of needle nose pliers with Corrosion-X and it's my goto spray these days. Yes, it still takes time to get full penetration but it is the best I've found so far.

 

[RoyS]

Start with the understanding that all penetrating oils are overrated and go from there.

 

[sailme88]

I've had great results with Castle's Thrust..

 

[jssailem]

While recently taking my 1973 Perkins 4.107
apart so it could be removed from the boat, I used PB Blaster on a few of the rusted fasteners. It worked but the fumes made me gag and persisted from to many days. I replaced the PB Blaster with Deep Creep Penetrating oil. Much more forgiving and usable product. (IMO)

 

[Project_Mayhem]

I read a test (don't remember where) but their first pick was 50/50 acetone and transmission fluid.
Have used most of the suggestions above. Also have had to resort to a nut splitter if there is room. Otherwise I drill a hole down thru the nut parallel to the bolt and missing the threads on the bolt. Start small and enlarge as needed. Final removal is using a cold chisel.

Here's the source: OT - Penetrating Oil

 

[Mechone]

Knockerloose #1 CRC Chemical Solutions - Knock'er Loose Penetrant - YouTube

 

[Crusty Ol Salt]

Back in the day we used wintergreen oil.

I am a PB blaster guy these days

 

[danooxnard]

In applications where you can apply a little heat, bees wax is the best!

dano

 

[Mark Maulden]

Plain ole diesel..

 

[Mechone]

Knockerloose #1 CRC Chemical Solutions - Knock'er Loose Penetrant - YouTube

I can tell as a millwright for over 40 years ,I've used them all and Knockerloose and Wurth Rost off are #1,then all these snake oils . I have lossened 1000's of bolts

 

[SeaCure]

I don’t believe you can give a proper answer until you know what material is the bolt made of and what is it bolted to.
if you add penetrating oil to a stainless bolt stuck in aluminum if will do nothing. Enough penetrating oil left in a stud hole will compromise the locktite.
Id guess most stuck bolts on a boat are stuck in aluminum or cast iron. Cast iron being out long obsolete transmissions and engine blocks. Sailboats seem to be the last vehicle who regularly use cast iron anywhere.
aluminum with a stainless bolt fused in it diluted drain cleaner or any mild alkaline will break the bond. Penetrating oil or heat will make it worse.
pS WD40 sucks in dirt and is a poor lubricant. Pure marketing