I'm gonna take a stab at this one... On three seperate occasions I've noticed an oil to impact the running temperature of my FZ6. It has a temp gauge and reads directly in degrees, and I pay close attention to it. First off, the most recent event, I switched from Valvo prem. blue (15w40) to Mobil 4t racing(10w40). Took the bike on the EXACT same route as an hour before the oil change. The conditions were exactly the same, the bike started the ride at the same temp. There is about a 10 mile section of road that is straight, flat and devoid of traffic (at least on this occasion). During that stretch the bike will run around 180 deg F. On the new oil the bike bottomed out at 192. Not exactly a controlled, scientlfic test, but as close as I'm likely to get. Being rather disgusted with the Mobil, I rode the rest of the way home with the average temp running 8-10 degrees higher than I normally see, then dumped it, drained the oil filter as well as I could and refilled with more Valvo prem blue. Rode the EXACT same route yet again, same day, same conditions, and the temp returned to the same as it's been with every other oil I've used in the FZ6. O.K., so I'm convinced there's something to it. There's a guy over there on the grassy knoll, and he's got a gun! Not exactly earth-shattering oil-conspiricy-theory, but it isn't the first time a PAO based oil has made one of my motorcycles seem to run hotter. The other times involved Mobil 1 15w50(old formula) and Repsol syn bike oil. Different bikes though, and I trust the temp reading from the FZ6 as gospel, as it's super-consistant, hence this anecdote from the Mobil racing 4t. So we all know that different materiels handle heat transfer differently. For instance, water transfers heat better than water+anti-freeze. Oil is a major contributor to heat dissapation in an engine. It's not a stretch to think that the heat transfer properties of oil "A" may be different than oil "B". It has been said that certain oils have a "polar" effect. That is to say their ionic charge is opposite the surfaces they are lubricating/cooling. If we use an oil that has less of a polar effect, or perhaps a neutral or even similar ionic charge to the engine surfaces it seems likely that the oil would not "wet" the surfaces of the engine, thus not transfer the heat as well. After having said all that I feel kinda bad because it's just an arguement in my head that I've convinced myself of. These days anyone who has a reasoned-sounding hypothesis... Ahhemm, engine break-in proceedure... Cough-cough..Motoman... is automatically an expert. I make no such claims. I only seek to say to Mr. James_Lesiar, his experience sounds familiar... Try a different oil!
