Penetrating Oil 2018 Test: Which Brand Wins?
In our 2018 test we compared 6 penetrating oil options head to head. Liquid Wrench came out on top. See the measured results, the runner-up, the budget pick, and a link to the full test video.
Liquid Wrench
Price shown in test: $4 a can, least expensive product tested
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ATF/Acetone
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Liquid Wrench
Price shown in test: $4 a can, least expensive product tested
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The quick take
The short version of why each pick lands where it does, built straight from the measured results.
“it's very clear that some products are better than others and in this case, the least expensive product at $4 a can, Liquid Wrench, beat all the competition”
The measured results
Every number below is read straight from the test. Products are listed in the order they finished.
Soak Observation 1 Hr
- 1Liquid Wrench
very much like the Kroil, appears absorbed down into the threads or evaporated off; reviewer could not visibly tell if it had dissolved more rust than the Kroil, describing them as looking about the same
- 2ATF/Acetone 1:1 homemade mix of synthetic automatic transmission fluid and acetone
a lot of oily film still left behind (attributed to the ATF), which the reviewer suggests means it would keep working its way into the threads over time
- 3Royal Purple Max Film
compared to PB Blaster, more of the product was visibly left on the threads and nut
- 4WD-40
very clear that a lot of WD-40 was still left behind; the reviewer notes it does not evaporate off as quickly as the other products tested
- 5PB Blaster
did not have as much film left behind as the Liquid Wrench or Kroil; described as a lot drier
- 6Kroil AeroKroil
most of the product appeared either evaporated off or absorbed down into the threads
Claim
- 1Liquid Wrench
claims to dissolve rust and cut through grease
- 3Royal Purple Max Film
synthetic penetrant lubricant claimed to provide good wear protection, prevent rust and corrosion, and loosen rusted and stuck parts
- 4WD-40
claimed to lubricate, protect from rust, act as a penetrant, and serve as a water displacement product
- 5PB Blaster
claimed to be the number one selling penetrant, breaks free rusted and frozen parts, protects against further rust and corrosion, and attacks rust from all angles using capillary action
- 6Kroil AeroKroil
claimed to lubricate, remove rust, clean, and prevent rust; big claim is that it loosens frozen metal parts and can creep into openings as small as one millionth of an inch
- 2ATF/Acetone 1:1 homemade mix of synthetic automatic transmission fluid and acetonenot tested
All measurements (1 more)+
Recipe
- 2ATF/Acetone 1:1 homemade mix of synthetic automatic transmission fluid and acetone
one part acetone to one part synthetic automatic transmission fluid
- 1Liquid Wrenchnot tested
- 3Royal Purple Max Filmnot tested
- 4WD-40not tested
- 5PB Blasternot tested
- 6Kroil AeroKroilnot tested
How it was tested
- visual film/rust observation on the bolt threads after roughly 1 hour of soak time
- breakaway performance after soaking (first four bolts used untreated as a control; 28 rusted grade 8 1/2 inch lug studs, torqued to 100 ft lbs before rusting, used across the six products with two doses of penetrant applied over about 3 hours of soak time); no numeric torque results for this test are stated in the transcript
- comparison against applying heat/torch as a non-penetrant alternative (qualitative only, no numbers given)
“it's very clear that some products are better than others and in this case, the least expensive product at $4 a can, Liquid Wrench, beat all the competition”
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