High mileage 10W30 Castrol or Pennzoil is different than other 10W30 (And the other brands High Mileage I've tried run like regular 10W30) Seals up great after about a week of driving, and apart from topping up the first week or so until it runs in, it might not need a top up on 6 months 5000 mile changes. It's honestly like a new motor with it. Even 20W50 was using a quart every 1000 for me before. It's double the price of regular per jug but long run it works out same or cheaper.