This week on The Best of Car Talk, Tim doesn’t know if he should be worried about the substance on his Fury’s dipstick, or if he should just make a tuna salad sandwich with it. Elsewhere, Tonia likes her next door neighbor but is less fond of the noxious chemicals he uses on his car; Larry wants to convince his wife it’s okay to buy a used car from a rental company but a tale from Ray’s past may change his mind; and Dara is having trouble selling a car that used to belong to the fire chief. Should she forget about selling the car and just advertise its spotlight and chief's hat? All this, plus the great Cathy/Kathy challenge, and more this week on The Best of Car Talk.