XRAY - Model racing cars

The problem with using different brands of fuel is that the different oils can react with each other if you don't flush out the engine before a fuel switch.
I've seen this happen and it's not pretty.

+1 for Rocco's way.

I broke in my last two motors this way and they are the smoothest best idling motors I have ever run. They are maxpower C5Q's and the buggy motor is north of 6 gallons and runs 9 1/2 minutes per tank at 235 degrees.

so the purpose of "breaking in" one of these ringless engines is that is the best way to get the piston perfectlly honed to fit the cylinder. Since there are no compression rings these engines need to run at a specific temp .
I always wondered why no one used a high oil content fuel to lubricate and flush any metal shavings out of the engine. thanks you rocco