There are reports of noisy, slipping and dragging clutches, not necessarily all at the same time, of course.
The 668 is a 'unit' contruction engine, with the same oil lubricating the engine and gearbox. This places extremely high demands on the oil, as there are conflicting requirements for each area. The gearbox requires an oil that can stand up to a lot of 'thrashing', as it is repeatedly crushed and sheared by the gear clusters. It also has to flow well to get to the top of the engine, stick well to parts that are very hot to lubricate them, and not be too thin and weep past valve stems and piston rings. Added to all this, the same oil is also present in the clutch area, where it acts as a buffer between the clutch plates.
The reason for concentrating on oil characteristics is this - to make sure your clutch works as well as it can, with as few problems as possible, always use a high quality engine oil! The Agip 4T recommended by the factory appears to be no longer available, but good quality alternatives such as Mobil Super Racing 4T, Motul 4T and Quaker Slate are all very good substitutes. Don't skimp on the oil, or the first thing you'll notice is poor clutch performance. Also, further down the track you'll start to see other problems, but that's another story!
© Steve Carr, 2001-2007
Site created February, 2000. Last modified Friday, May 15, 2009
30 May 2005