A formula designed by Styria - whether it be effective may well be open to question from various sources, but naturally you try your best according to ability, knowledge and equipment. The following procedure I have carried out on Gleaming Beauty, and will now also be carried out on the Astral Silver 6.9.
Obviously, the ideal time is when the heads have been removed, as it exposes the bores, the timing chain apertures and, in due course, you drain the sump and also the engine oil reservoir...