Dumb question, cold starting...?

So I am currently running Valvoline conventional 10W-40 for break-in but like I said the hot oil pressure isn't quite as high as I'd like it to be. Once the engine passes 1000 miles I'm going to change the oil, AutoZone was having a deal on Mobil 1 oil and filters so I bought five quarts of the 15W-50 formulated for "performance vehicles". Is this a good choice or will it be too thick for my street engine?