LoK nay?! The x in Wikipedia's pronunciation guide from the link above is pronounced like the ch in Scottish loch or the German composer's name, Johann Sebastian Bach. Neither is a k-sound.
Well, of course, Aston, people MISpronounce things in their own way based on geography, but Chambers Dictionary's pronunciation-guide for the word is lohh...ie the ch sound I already outlined...and The Oxford English Dictionary uses the same x-form as does Wikipedia. Assuming Oleanda wants the RIGHT pronunciation, the x/ch one is it. Cheers