Call me cheap but tomorrow I am gonna clean the air filter. Take it out washing up liquid clean and then re-oil, I have looked here http://faq.ninja250.org/wiki/How_do_I_clean_the_air_filter(s)%3F and they recommend K&N oil but say any oil will work and the guy is simply using left over clean engine oil. Obviously with changing my oil today I have some clean oil left and I'm wondering if I can use it. I know its only saving me about £15 but still its better than nothing. Does anyone else just use normal engine oil on their filter?