I really hope the signal-to-noise ratio on this forum doesn't deteriorate due to this, but here goes. After lots of research here and elsewhere and preparing a spreadsheet comparing various candidates for my upcoming oilchange, I believe Red Line 5W-40 is the ONE oil for me if I have to choose ONE for year-round use. However, I'm now considering using 2 oils during the year--RL 5W-40 for our mild 'winters' in Phoenix (where it rarely even reaches freezing), and RL 10W-40 in the 6-month summers. I drive about 20,000 miles a year, so changing twice a year would be about perfect. (Porsche recommends M1 0W-40, 5W-40, or 5W-50, changed every 20,000 miles, and I'm now early in the 2nd batch of 0W-40 which was installed at c. 11,000 miles.) I'm tending toward the 10W-40 in summer because it gets REALLY hot here* and this oil has NO VI improvers so ought to have a little better High-Temperature, High-Shear performance. Also, I've installed (but not yet plumbed**) an OilGuard bypass filter to help keep the oil clean between changes. Does this make sense? * as in DOWN to maybe 85dF around 4am during a not-untypical summer nite in June thru August. ** I'm waiting until I receive my extremely expensive shop manual before connecting it--the engine is REALLY complicated.