is PLA gasoline, diesel or chemical resistant? can PLA be used to print out containers or other parts that are in direct contact with gasoline, diesel or other hard chemical substances? Will it start degrading when in contact with said chemicals? Should I use ABS for this?
I have used both ABS and PLA for diesel gas caps and oil plugs.  As well have made a gasoline funnel out of both.   Both have done well for me.
I have attach a link to a plastics resistance chart if it is any help.  Unfortunately it does not show testing for ABS for all.  

I prefer the ABS only do to the fact some items I have made sit in the desert sun.  

Plastic resistance chart