Your scope is an expensive piece of coated optical equipment. You should treat the lenses with the same care you'd give to a pair of coated eyeglasses or camera lense. Just my opinion - but after f&*^ing up both, I decided not to take shortcuts with any of this stuff.

Go to a decent (not big box) camera store and buy the stuff they sell to clean camera lenses. This includes - liquid, cleaning tissues (or cloth) and a blower brush. This is not a big deal to buy or carry. It is tiny, light weight and cheap.

Having said that, the principle is: remove any grit (with blower brush) then clean with appropriate solution and tissue/cloth. Knowing this, you can improvise as long as you follow the principle - get the grit off by blowing or gently brushing with a clean soft cloth, then cleaning with an appropriate liquid and appropriate cloth. Breath fog and a clean soft cotton shirt tail will do. Don't use any paper product not designed for lenses as they could scratch.

If you have oil spots, I'd get some lense cleaning solution and try it. If it doesn't work, I'd ask at a camera shop (again, one with expertise, not a big box).