since you have allready 400 hard miles, go ahead change the oil and the filter, make sure its warm when you do this, and let it drain completly, then replace with whatever oil you plan to run.
normally you can take it in steps, but most likely you have everything pretty much broke in, the thing to kinda stay away from is redline pulls for the first 500-1000 miles, take it to the upper rpms, jsut not at full throttle or a constant top end run, after say another 500 swap the oil again, at that point if you want you can grab a sample and get a sample kit from napa or catapillar and have the oil checked to see if there is any premature bearing piston or ring wear
Or you could get a sample kit from Komatsu/KOWA (NOT CAT). I use them on my vehicles, of course I work for a komatsu dealer, so the KOWA samples are readily available to me, and can't beat the price
what size of oil will best for this((???))) ..next run regular oil or synthetic oil
how many qt of oil will a viper eng take
Just from personal experience I would not hammer on a new engine to much. I built a 302 Ford years ago and beat the hell out of it right away and tore the cam up.
what size of oil will best for this((???))) ..next run regular oil or synthetic oil
how many qt of oil will a viper eng take
Long beach
Off the 91. On cherry st.
Were you from sperm receiver. What state ???