Your Question . . .

"Can I just dump a gallon of vegetable oil in my cars tank?"

NO !

A little more reading is in order.

and this

"Would I just be better off with Howes or Diesel Purge? "

YES !!

I'm terribly sorry now that Bio-Diesel was mentioned on this particular thread.
It has absolutely nothing to do with the other products that clean injectors etc.

Headstill mentioned BioDiesel in passing and I took him up on it, that's all.

I think we had better start a new thread on Bio Diesel if we are to continue any discusssion so as not to confuse people.

jim.