My Pre-Cat sensors had to be replaced at 260,400 miles. I only use Shell gasoline and no additional fuel additives. Apply your funds to other maintenance issues such as the CCV system and cooling system. At your vehicle age and mileage it's time for expansion tank, main hoses and belts.

2002 X5 3.0 305,200 miles
2014 428i 19,500 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird Under restoration