I bought a second hand 2004 VTR250 some months back and the previous owner hadn't used it for quite a while (8 months plus). One of the first things I did was change the oil and filter. The oil that came out was black and had a lot of sludge in the bottom. Dad advised me that if it was that bad, get the bike good and hot (like a good run on the free way) and then change the oil and filter again. I did this on Sunday after around 1000k's on the new oil and the oil that came out was dark brown (not black) but wasn't transparent and had a sort-of opalescent sheen. Is this normal? I've only ever changed oil on diesels which goes black 2 seconds after starting the engine so I'm not sure what the newish used bike oil should look like. For reference, I used Castrol Power 1 GPS 4T in the gold bottle. Otherwise the bike runs fine, the plugs are in great condition with a brown tip and blackish end and the air filter is clean. It doesn't use any water or oil and starts very easily. Bike has some 38,000k's on it.