Motorcycle Repair: gas in oil, bmw r 65, yellow dye

Question
hey, i was recently given a bmw r-65 motorcycle by my father. he has had the bike in storage for about four years, after trying to change the oil filter ond change the oil he had difficulties on a ride. the bike became hot, the oil light came on. he shut it down at once and had it towed home, where it sat in storage . i recently tried to ressurect the bike and thought i would start by changing the oil/filter and see if he did something obviously wrong. when i dropped the oil plug the oil that came out seemed very thin. upon closer examination i found the oil to be contaminated by what appears to be gasoline. i was wondering if that is something that happens with a bike thats been stored that long,should i do the oil change / filter or is that a sign of a more serious problem any insight would be appreciated. the bike is a 1980 bmw r-65

Answer
Hi Kris.

Did the oil smell of fuel?
 If it did, then it was fuel in the oil.  However, chances are that what you may have seen was water, which could have accumulated over the past 4 years in storage.
Had it been there from the beginning, there wuld be a white material mixed in the oil which is a fungus that grows in petrolium when there is long term water intrusion, like water in the oil and then storing it for years.

 Gas has a very distinct color to it as well as a very distinct smell.  Normally it is clear, like water, but the petrolium manufacturers worldwide did not want to get it confused, visually, with jet fuel which has no dye in it.  so gasoline has a yellowish tint due to the addition of a yellow dye at the refinery.  You would not likely see the color difference for the fuel if it was in the oil, so you would have to rely on smell to know for sure.

You should, absolutely, do the oil and filter change.  But you need to flush the engine before putting in the new oil.

The original overheat could have been because of something blocking a port for the oil to flow, so, usually, flushing the engine will help or fix it altogether.

Don't forget the remove and properly clean the carbs as well as resealing the fuel tank to prevent contamination of the fuel system.  Over the years, while in storage, varnish will have developed in the fuel tank, fuel lines and carbs.  Those steps as well as replacing the fuel lines will prevent problems later on with the carbs and fuel system.

Let me know what happens and if the overheat comes back.
Good luck and ride safe.
FALCON