Oil life?? Time vs. mileage ....

I have spent most of my life working in the oil industry and i must say i agree with all of you , everyone that posted comments here is right in one way or another. The main reason that we have 7500 mile oil intervals is purely dollars and cents , its all about making the yearly maint expense as cheap as possible . In many cases they can get away with the 7500 interval and in the cases they cant the OEM has considered the warranty repair an expense of doing business. Compared to 5 yrs ago the additive package in oil today is very sensitive and like one person mentioned its not will the oil wear out its how much dirt and moistue it absorbs. There many good additives you can use that are designed to treat the matal not the oil ( Justice brothers 23P,BG 44MOA,Z Max) these products use the oil as carrier and treat the lubricated surfaces of your engine so if the oil loses its lubricity the damage will be avoided . If you run a Holley or edelbrock carb , or really a card in general your oil breaks down quickly due to fuel contamination . in our old muscle cars oil break down is excellerated by heat that is created by our need to constantly excellerate , after all thats what our car were made to do . One other topic i would also mention is synthetic oil in a musle car , in a car with a carb , due to contamination synthetic is a waste of money , it will be diluted with fuel and dirt long before its advertised 7500 to 10,000 mileage life . Myself i change the oil in all of my own cars and trucks every 2500 miles, its cheap insurance for an expensive piece of machinery, many will think im crazy but i have found this formula has given me nearly maint free cars and truck for a long time .You wonna remember the manufacturer does not have in you in mind when making recommendations, they want you to buy a new car . So a longf lasting car does not fit into the big picture . As far as oil being better then then it ever has , i could not disagree more with that mind set. The new additive packages they oil companys are using are very fragile and often make oil worse not better .