I found that shell is producing a 5w20...I currently run their 5w30 on 5k OCIs with good results.
Would there be any benefit to running a conventional 5w20 over a conventional 5w30?
I think that most cars that call for 5w30 would be better off running 5w20 in the wintertime, especially those that do shorter trips that don't get the oil fully up to temperature anyhow. 5w20 will definitely flow quicker on a cold start than a 5w30, just by looking at the viscosity at 40c you can see how the 5w20 oils get a bit more of a headstart at thinning out compared to 5w30.
Not unless your vehicle specifies 5W20 (My honda does).
SO does mine.. 5w-20 from factory and am enjoying it quite well in 5w-20 land. Just got 26.4 mpg doing 100% city.
I get about the same in the city in the TL and close to 34 on the freeway on 30wt. It actually feels a little quicker with the thicker stuff. Of course the figures go down about 50% when the girlfriend has the car for a few days.