Oh right, the dipstick being dry is normally a bad sign with these, if you don't keep them near the max, or atleast over the 'middle' of the dipstick, they do not like it. Mine's always kept pretty much on max! You may (and it's a slim chance) have got away with it, if you topped it up straight away, and it hadn't been driven hard whilst low. It's strange that it doesn't do it when increasing rev's, this'd be the first sign usually. These engines are VERY tappy, due to running solid lifters, which, as you probably know, wear, and create quite a bit of top end noise. Mine is appalling lol. What oil has it got in it currently? Generally a good quality 5w30 is all these need, unless being tracked and getting very hot. Thicker oil may make matter worse, as it will not lubricate sufficiently, due to the tight tolerances. Get a video up mate, let us hear the noise, as normally when the bottom ends go on these, you know about it! (I had one go, it was pretty obvious straight away )