Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
I live in Mississippi too and have been using conventional 5w20 Havoline oil and have had zero engine problems for 254,000 miles.
Still running on seven of the original spark plugs and coils.
5.4L 2v 4x4.
Knock on wood........original fuel pump, starter, alternator, water pump, power steering pump, and no A/C repairs. Replaced serpentine belt at 250,000 miles and the old one did not look bad.
I have been a user of Mobil 1 since it was released and I am here to say that I have ran it in high performance motors and the gamut down. I have personally torn down motors that used it diligently and I am here to say it is the best product on the market. As for the observation of weight, this is a optimized suggestion by the manufacturer. The motors are ideally built to handle this through their pumps and raceways...that being said...changing the weights and viscosity to further optimize based on environment is possible, but I would only consider this if I was experiencing cooling or lubrication issues. Regular recommended oil change intervals are again the optimized state, personally, I do oil changes based on miles and nothing else, I also consider driving conditions, 3500 mile changes in hard or towing conditions, and 5000 miles in normal operation...my $.02.