Def change it at 500 mile mark to Fully synthetic. Thats the perfect engine break in period. When i built my RB I waited until 804 Kilometers later (500 miles) Then switched to Eneos full synthetic. Everything was completely fine. As far as for the Dyno day. if your at the 500 mark, Change it. If not dont worry about it. You will only loose maybe 1 to 2 HP.