The Ultimate Threadlock How To

Posted by David Alkire on May 14th 2021


Hi guys, David here. Today we are going to talk about Threadlock and how to determine which color and strength you need for your project. Threadlock is an anerobic adhesive that is used on bolt hardware when you don’t want the bolt to loosen up and fall out due to vibration and heat & heat and cooling cycles.

For most automotive applications there are 4 strengths of threadlock that are at your disposal for use when re-assembling or repairing your car. They are Red, Blue, Green and most recently Orange which has the stated strength of Red with the removability of Blue. Confused yet? Stay with me here, by the end you will understand.

Threadlock is identified by the color of the liquid…not the bottle. Different manufactures of threadlock call out their products strength by different numbers or names but the products color is the uniform indicator of strength. Why is this important? Because for some reason some manufactures will put “GREEN” locktight in a “BLUE” bottle almost as if their marketing department has never had to use the stuff, right?

Now the important stuff; what do the different color threadlockers do?

Red threadlock is a high strength threadlocker and is for heavy duty or very high vibration applications that you don’t plan on taking off like….ever. Red threadlock will require Heat & Special Tools for disassembly. It will require 500+ degrees of heat before it will separate and should be used on assemblies that are to be joined semi-permanently. Common applications include cylinder block bolts, ring gear bolts and transmission stud bolts and it typically is used for bolts 3/8" - 1" in diameter. Red threadlock can be used to semi-permantly lock studs, bushing and fasteners.

BLUE threadlock is a medium strength threadlocker and prevents bolts from loosening due to vibration. Common applications include drive shaft u-joint bolts & various types of mounting bolts that may require future removal. Bolts with BLUE threadlock can be removed with hand tools and are typically used on bolts 1/4" - 3/4" in diameter. Blue threadlock will set up in 20 minutes and reaches full strength in 24 hours.

Orange threadlock is a hybrid formula that combines the stated strength of RED threadlock with the removability of BLUE threadlock. Common applications include flywheel bolts, transmission mounting bolts and case half bolts. Orange threadlock is rated as being 3x stronger than Blue threadlock and prevents loosening from vibration specifically. Orange threadlock is typically used on 1/4" - 1" bolts.

Green threadlock is a light duty threadlocker and is unique in that it is a penetrating grade of threadlock and is the only threadlock designed to be applied to bolts after assembly. Green threadlock utilizes a special formula that will penetrate the gaps in assembled parts and is typically used for #2 - 1/2" bolts.

If you had something fall off your car or have something fail due to a lost bolt you know that threadlock can be a critical component to building or repairing a car, motorcycle or anything mechanical that vibrates with enough force to loosen an untreated bolt. Hopefully, this article has been helpful in understanding how, what and where the different strength threadlock can and should be used.

For all your muscle car & truck performance and restoration needs please visit the always open, easy to use First Place Auto Parts website where you will find thousands of the best and latest parts for your ride. Don't forget to check out First Place Auto Parts on Youtube where I will be covering everthing from "How To" guides to the latest car enthusiast events!

Until next time, keep the hammer down and keep it between the guardrails! 

to top
Call Us