I have a 2 part question 1: Is it an absolute must High Mileage Synthetic Blend Oil must be used after a Car rolls over 75,000 Miles or no? and 2: What is the most a Car can go Miles/Interval wise when using High Mileage Synthetic Blend regardless of which brand is used?

Steve Clausen: It is never absolutely necessary to stray from manufacturers recommendations unless something has been modified or the type of driving is exceptionally different than average use.As far as the mileage intervals go the oil doesnt determine the intervals, the tolerances in the engine do. If the manufacturer recommends 5000 mile intervals then no oil will extend that.

Steve Clausen: The benefit of the high mileage oils is that they have additional additives specifically for older seals and worn bearings etc. They are also usually on the thicker end of their respective viscosity rating.

Ryan Chase Josemaria Pruitt: Interesting perspective Steve Clausen a friend of mine told me that Oils like that keep old engines lubricated much better

Steve Clausen: There are definitely benefits in running higher quality oils, but to say it is a requirement would be wrong. People should beware of a lot of the snake oil additives out there. And there are loads of misinformation when it comes to oil.