Ahhhh, THAT'S what you guys are talking about. I believe the official term for that would be the "viscous coupler" or something to that effect. For the unknowing - the cooling fan is not directly driven on many Deutz engines. There's an exhaust temp sensor that triggers oil flow into this coupler - the more oil that is allowed into this thing, the faster the fan will turn. Supposedly will allow engine to warm up faster, maintain a more steady operating temp over varying load conditions, and reduce fuel use somewhat since the fan isn't robbing so much power at light loads. I was wondering too what he was talking about - but figgered it was something on the V8s and we haven't had one of those. Belarus tractors used to have a centrifical oil cleaner instead of filters - no filters to buy, just clean the thing out at each oil change. Wonder how effective compared to actual oil filters though! Tom langan