My dad has a small construction company and one of his fleet vehicles is a 2000 Ford E-350 Super Duty. He wants me to change his oil from now on. I checked the manual and it asks for 5w30. idk but should I use a higher weight? this full size van tows alot as well as carries alot in the back. Sometimes it carries an entire pallet of cement from Home Depot. So what do you guys recomend for this burly workhorse? what weight and brand?