A lot of people disagree with engine flush completely! but if you are going to do it, like I did, then use a proper engine flush, done use anything that isn't supposed to go in an engine! I have a leon cupra mk1 180 bhp, it wasn't too ad to do, but it was made easier by having access to a ramp at work! the most difficult bit I found was the 4 bolts hidden up near the flywheel! but it is totally doable! in my experience working in garages, engine flush will break away the harmful deposits and drop them to the bottom of the sump, so I have only used flush as I was removing the sump, or them deposits get stuck in the oil pick up gauze!
anyway, what I did as, run engine flush at a fast idle for 10 minutes, drained oil, then reoved the sump and cleaned this and the oil pick up, and changed the filter, then replaced sump, new filter and fresh oil