First thing in getting the best deal on a plane, is getting an airplane that needs nothing.
Then look at insurance, storage, and annual costs.
I've found that when time is on my side during negotiations, I'm more likely to get the owner to come off his price.
Remember to ask for...
If your just getting fuel, I'd say no.
If you need oil, and he helps with finding a funnel, a clean rag, tire gage, etc... then yes.
Normally no.:nono: