your thinking of stuff that works the other way around for really tight clunky diffs, i use redline friction modifier because my diff is as noisey as f**k, and the noise went away. so to answer your quuestion, no theres nothing that makes it grip more, possibly normal non-lsd oil might
yeah, you can try not to welded it, convice yourself its not the best route... but you'll always find yourself with sleepy eyes at 3am with a your lighting rod in your hand, and splater everywere.
I've been told normal gear oil or engine oil will make it work better as it doesn't have the LSD friction modifiers, will be more aggressive on the plates but should lock better.
Basically with a stocko LSD it's not too much of a problem since they're not aggressive, the increase in plate wear isn't the end of the world, it's just with a proper/uprated LSD you really need to use the proper oil or they'll wear our superfast.