125k 2002 plate, 225 BAM here Stage 2 custom code generic map, (with full supporting mods) running triple QX 5W-30 fully synth here - Bought 1 litre to top up recently after a long trip. Never had a problem.
Always used an engine flush "in a can" when changing oil. Had the car 9 years (1 owner from new) he had servicing done at Audi Teeside.
Last night & muchos reading across the net / forum... Bought 5 litres of 5w-40 fully synth (same brand).
- Will change it in 2-3 months time / whenever it get low next. I agree, 5w-30 gets too thin at high temps.
It's all relative to our individual experiences.