3.3 V6 oil consumption and engine failure
These vans can burn oil fast with no warning light, and running low leads to knock and total engine failure. Check the dipstick against the last oil-change date and listen for knock on the test drive. Ask for oil-consumption test records; a knocking engine is a walk-away unless priced for replacement.
Ask for repair records covering this item. If it hasn't been addressed and the car is in or near the mileage window, price the $3,500–$6,000 repair into your offer — or make it the seller's problem.