for whatever reason this does seem to be an emotional rather than technical issue.
My experience has been that thicker oils keep engines alive longer. For those that think the newest engines are designed differently, check out the specs over at BMW. The M5 (redline 8k)requires Castrol synthetic 10-60 oil. Using 5-30 voids the warranty.
The A3,B3 oil specs called out in the owners manual of a 2002 VW 1.8 turbo Passat translates to Mobil-1 0-40 oil ONLY. 5-30 etc doesnt cut it. Penzoil tech responded to an info request and indicated the only oil in their lineup that passes these specs is Penzoil Syntheic 5-40.
I have seen recent posts indicating M1 0-40 is becoming the oil of choice for turbos. Must be an increase in demand during the past year - even Walmart now carries it here in NY.
I ran the last batch of 0-40 in my SE Sport for 12 months & 11.8k miles. I dont rely on pet theories tho- I back it up & used oil analysis indicated the oil held up fine. Not surprising since this oil passes MB latest spec on extended oil drains.
There is much good info over at bobistheoilguy.com
