Its not very common to use multigrade suspension fork oil although it is done.

How do you find it in comparrison to straight single grade ?

I cant really tell,I would never use multigrade in a fork but as the guy explained to me Its a synthetic oil that thickens when warmed up so it
gives the effect of stiffening the suspension when it is working hard,intented for mx bikes.
Altogether with wp springs front and rear its so much better when riding hard i cant find the words to describe..Almost like a new bike!