Everyone's LS motors seem to like a different oil. Mines done 175kms and ticks if I use thicker oils. It's fine running full synth 5w30. Thicker oil is not always the answer. On another note, no oil will cause gumming or sludging if you always use the same oil and change it regulatory. Using different brands is was causes build up in engines (and prolonged intervals of course) Doing a flush before changing brands helps this issue. So any decent brand is good as long as you change it regularly and stick with same oil once your happy with it. This was the advice given by an engineer friend that had done a course in lubricants.