Yeah, the pellets are responsible for a lot of the sludge found in commodore coolant bottles etc, in the past. But no-one uses them anymore so the residue should be well and truly flushed out of the system. The head gaskets on the VR are not prone to failure! The intake manifold gaskets on the VR have a tendency to fatigue and fail, allowing water to seep into the engine. Not a big problem if it's a slow seep. But worth fixing. Have a look at the joints between the manifold and the heads - if you see any beeds of water, then the gaskets should be replaced.