An outer tie rod is bound (screwed into) the inner tie rod as described in this previous posting.
WD40 was sprayed at connection between the two tie rods and the jam nut was loosened. Attempts to unscrew the outer rod were unsuccessful. Is WD40 a good penetrant or is it merely a lubricant and I need to use another product? I am open to suggestions.
http://www.jalopyjournal.com/forum/threads/best-penetrating-oil-for-stuck-nuts-bolts.773380/
There was a study done on penetrating oils. Here's the highlights -
The break out torque required for:
Nothing = 516 ft. lbs.
WD-40 = 238 ft. lbs.
PB Blaster = 214 ft. lbs.
Liquid Wrench = 127 ft. lbs.
Kano Kroil = 106 ft. lbs.
50/50 blend of ATF and Acetone = 50 ft. lbs.
WD40 is not a penetrant, and as far as lubricants go, it's a poor one. Get a legit penetrating oil at the car parts store. They come in spray cans and range from $7 to $15.
WD40 is specifically designed to disperse water (hence WD). It is useful as a penetrant, lubricant and solvent and this versatility if one of the reasons why its is so popular and useful and versatile ie a can of WD40 in your tool box will do a lot of jobs reasonably well.
However there will also be more specialised products which perform specific functions better. For example in the case of a stuck tie rod you may be better off with a specialised penetrating oil.
WD40's main use is actually as a water dispersant hence the WD, however it is also a anti-corrosion, penetrative lubricant and is excellent for helping free up seized nuts/bolts etc.
I just found WD-40 Penetrant.
https://www.amazon.com/WD-40-Specialist-Release-Penetrant-Spray/dp/B0083V8JP6