If my main concern is keeping oil consumption to a minimum on my Ford 4.6L v8 modular engine with 85,000 miles, which of the following is better? -Castrol syntec 10w-40, or -Mobil 1 0w-40 -Pennzoil High Mileage 10w-30 and 40 -Which one is the thickest and thinnest oil? -Which one is safest for old seals? I'd appreciate it greatly for opinions asap. Have to change oil in 24 hrs.... Thank you all so much!!!