I believe the 7500 and 5000 mile intervals that you're quoting above are for our Stangs and based on the synthetic blend that they come with from the factory. I concur with those numbers and in previous threads I have also spouted that philosophy. However, with a good full synthetic those intervals can be extended. Personally, I use 8,000 miles for what I consider "severe" duty (running the Stang hard frequently; towing with my SUV) and 10,000 miles for "normal" duty (infrequent under 10 mile starts and stops; mostly mild to spirited driving) using a quality full synthetic.

Based on my experience with oil analysis in the nuclear industry and discussions with those providing industry training, we're all "flying blind" regarding the true condition of our oil. All of these #'s for intervals being tossed around are very conservative and simply guidelines (and good ones for that matter, since we have little else to go by despite all of the chest thumping claims by various parties) unless you go to the effort of pulling samples and having analysis performed.

These threads regarding what to use and how often is an indication of how the consumer is baffled by the oil companies hype and the car manufacturer's disclaimers. I hate to see people throw their money out needlessly but "disinformation" forces many into too conservative of a comfort zone.

 

They are, and it would be reasonable to expect that the oil type, grade/viscosity rating, and change intervals have been selected with things like some acceptable anticipated rate of warranty claim and possibly dealership service department activity in mind.

Other than direct trial and (hopefully not) error experience and anecdotal comments here and elsewhere, most of us don't really have enough to go on to establish different limits that remain within individual risk tolerance. That said, I won't get all nervous if I find myself a bit past either the 5000 or 7500 once in a while (depending in my case so far on the percentage of extended highway mileage).


With respect to consumer understanding re: oil - I knew a guy (a designer by trade) who got horribly nervous because at one oil change in his fairly new vehicle his sump was overfilled by about 3 fluid ounces, to the point where he eventually bled that much out after three or four days of agonizing over the whole situation. Not a Mustang, or a Ford, or even a US domestic vehicle - but still . . .


Norm

 

I'm with you, Norm...

 

^^^+1