This is the misconception , LongLife III is 1 Centistoke thinner @ 100 °C than Platinum .
LongLife III is 0.50 Centistoke away from being a 40 grade .
But LongLife III has oil performance advantages over Platinum for wear , fuel economy ( also relates to power and torque increases due to extra friction modifiers in the additive package ) and the old 1.8 T issue of sludge .
You'd be surprised. Audi recommend the 5W-30 mentioned above for the R8. Ferrari for their 458 and Porsche for the 911 GT3 RS recommend 5W-40 and 0W-40 respectively - and these cars have their red line at 9,000 RPM. The stability/quality of VAG's 5W-30 (504/507) is such that you don't have to climb up the viscosity ratings because the car is either sportier or driven more "enthusiastically".What oil do Audi / VW race on I wonder , that would give a hint , which way to go ?
..for racing it would yeah
<tuffty/>
Racing has very different demands on oil to a high performance road car... I run 5W40 ester based oil, Bill runs 10W60 ester based oil in his race car... main difference is sustained load on the engine... just because my engine can produce nearly 600hp doesn't mean I am using that all the time... race car is different as you are on it all the time for 15/20mins or whatever race duration may be...Whats the difference , if the engine's over its normal power levels, whats factored are in on the lube side ?