what oil should i use!!!!!

[Phil TK]

i know some peeps say fully syn is waisted on the fazer however at that price i thought its too good to turn down, so ive got enougth for 4 oil changes .
 

You could always mix it with purest mineral Castrol GTX, it would go even further then
 Keep it quiet, but I used GTX in the Fazer for 3000 miles during a particularly skint period in my life. It was a leftover can from the time I had a Gpz500S (putting in a higher spec oil would have doubled the value of that bike).  Truth be told I had meant to change it soonish but forgot, and left it untill the next oil change, it didn't seem to hurt the engine, no overheating in traffic or anything. I never got round to checking the numbers on the back of the GTX can so I'm not sure if it was technically suitable. Probably isn't.

[Falcon 269]

I ran a Volvo 240 GLT estate for 225,000 miles over 16 years on Castrol GTX 20w/50.   Changed every 5k miles, never burned a drop in all that time.

You can be fairly sure that the additives in that particular brand name of oil have changed in that time but once again, the key here is the oil change interval.

Essentially, any oil has a life expectancy in use - and dependent on type of use - beyond which its viscosity at operating temperature falls as a result of shearing and other chemical reactions within the oil.  In extreme cases, and I mean extreme, the oil eventually loses its ability to prevent metal on metal contact under pressure. 

You can run on basic mineral oil without causing any more wear or damage than the most exotic synthetics provided you change the mineral oil before it reaches the point where its viscosity index under temperature/load falls below the minimum required.