I`d like advice please (re ceramic wall tile adhesive.?

i have a 16kg tub of `sovereign ceramic wall tile adhesive` ive had this tub for 3 yrs ( kept in storage) I opened it tonight & there was a thick crud on the top, i scooped the thick away & the bottom half seems ok (its still soft & oily) would this be okay to use on my ceramic wall tiles or will i have problems with it?.. thanks