Well I have just done the valley gaskets. When you drain the oil and it looks like chocolate custard, that's bad right? lol. She's a VS with about 240 K on it.
Old owner swears oil was changed often, but in the valley, sludge on the sludge, damn. Still engine sounded healthy and no smoke, just drank a heap of coolant. I only drove it a couple of times, then parked it for a while, now this weekend she will be back running.
I cleaned the sludge out of the valley with diesel and a brush, then flushed the valley area and out through the sump with a couple of litres (diesel) as well. Then put cheap oil in and ran it till warm, drained it and refilled with some 10-30 I got on special. Filter change as well, just as well supercheap filters are only 8 bucks odd! Will do a run around the block then change it for some castrol edge 5-30. Scored that on special as well can't complain.
My theory is the thinner oil will flow around really well, and being the good stuff should slowly help clean the gallery's of any goo hanging around, plus it's what Castrol recomend anyway, so can't do any harm right?
Got me why most oil sites recommend 5 or 10-30 and penrite recomend hpr15, 15-60, it's a big difference don't you think?
Anyway fingers crossed, I will let you know how I go !