If you are running in a new or rebuilt engine never use a semi or fully synthetic oil as these types of oil are so good at preventing wear that they actually stop the engine from running in & in some cases could seriously damage it, so use a multi grade oil when running in.

OIL-EN-RUN Running in Oil for dyno use 5 litres.

OIL-EN-MIL-10W60 Millar 10W60 Competition Fully Synthetic 5 litres (shown left)