I've been using Loctite anaerobic sealants for at least 25 years.
Google is your friend.

Loctite 518 will be Loctite 518 no matter what color the tube.
http://tds.loctite.com/tds5/docs/518-EN.pdf

Note .25 mm gap filling ability.

Use Loctite 515 for better resistance to motor oil.
http://tds.loctite.com/tds5/docs/515-EN.pdf

And...

http://www.henkel.us/brands-and-solutions/adhesives-sealants-surface-treatments-6072.htm

Note some of the other products made by Loctite's parent corporation.

Jim

On Mar 5, 2010, at 3:13 PM, Max Wellhouse wrote:

> Dylan:  is there a difference betwen the stuff in the blue tube and
> the red tube>  I'll feel stupid if when I open it up, it squirts red
> just like the red tube of 518 the mech. had.  I never figured out why
> Permatex uses the blue tube for both the red and blue thread
> locker.  Maybe that thinking has bled over to the 518 stuff.
>
> DM&FS
>
> At 08:29 AM 3/5/2010, dylan wrote:
>> I have known about it for a very long time.
>> Porsche engine cases are put together with it.
>> I use it on all orings and mating surfaces throughout the
>> waterboxer and Sub.
>> Benny Boy has written about it, but hasn't named the product exactly.
>> It is what he uses, along with other stuff when sealing.
>>
>> dylan
>>
>>
>> From: Max Wellhouse <dimwittedmoose@CFU.NET>
>> To: vanagon@GERRY.VANAGON.COM
>> Sent: Fri, March 5, 2010 3:12:38 AM
>> Subject: Loctite 518 uses on Vanagon?
>>
>> Anyone have a use for the anaerobic sealant from loctite called
>> 518?  I've seen it in red and blue,but the NAPA guy didn't seem to
>> know a lot about it or the differences between the red and the
>> blue.  The local Subie tech says it's great for assembly of the subie
>> motors however.
>>
>> DM&FS