This is something hard to find locally as you're experiencing, and I recommend buying and carrying a bottle with you, so you never have to shop for it at the last minute, and can tell a shop "Use this!"
There's a better Loctite product,more suited to splines. From this thread:
Hi Guys I have read a number of posts on the forum regarding what lubricant to use for the Drive Coupling Splines, and the scarcity thereof. Here in UK it is even harder than US to find moly grease and paste with the minimum levels of MoS2 recommended by Honda, so I decided to look around for...
www.st-owners.com
EDIT: There is another Loctite product (LB 8103) that is NLGI class 2. Here are differences between the 8012 and the 8103:
LOCTITE LB 8012
LOCTITE LB 8012 is a black, metal-free anti-seize lubricant with MoS2 and rust inhibitors in a brush top form. Formulated to protect assemblies during running-in periods, it resists high static loads and the MoS2 paste ensures maximum lubricity. It has an NLGI grade of one and is resistant to temperatures up to +400C.
• Metal-free
• Protects assemblies
during running-in period
• Resists high static loads
• MoS2 paste insures maximum lubricity
•
NLGI Grade 1
• Temperature resistant to +400C.
LOCTITE LB 8103
LOCTITE LB 8103 is a black, mineral oil and MoS2-based grease, which is suitable for heavy loads, withstands vibration and can be used on moving parts at all speeds. It is used in high stressed joints, plain and roller bearings,
splines and socket joints, and slideways subjected to vibration and heavy loads. . It has an NLGI Class 2 rating and can withstand temperatures to +250C.
•
Suitable for heavy loads and withstands vibration
• For moving parts
at all speeds
• For higher-stressed joints, plain- and roller bearings, socket joints and slideways
•
NLGI Class 2