Originally Posted by bobs
No offense, but the engineers at Mercedes-Benz know a helluva lot more about oil & engines than anyone here on this forum, and I tend to trust their recommendations. If you'll read the post above, you'll notice the FSS takes a lot of things into account when it calculates miles remaining before the oil change, so sometimes it will be more or less than the recommended 6,000 mile interval. Either way I'll venture to bet that its calculations are on the conservative side.
Unless you can provide some documented proof that going 9k between oil changes is harmful I would suggest that you don't believe the hype. I say that because the whole concept of the "every 3,000 miles" oil change was developed by the guys that want to sell you oil and filters, not the manufacturer of the car/engine.
The manufacturing tolerances of modern engines are so much tighter than in the past that much less blow-by and contaminants get into the oil, and so the interval between changes can be longer.
Just my two cents on this one...
While I agree that the Jiffy Lubes of the world want you to change the oil more frequently; every 3K miles; because it makes them money; the car manufacturers also want you to buy cars more frequently.
So it is in their best interest to have the car wear out sooner rather than later. And preferably have it wear out right after the Warranty expires. The conspiracy theory side of my brain thinks that the auto companies have this down to a science.
I am sure Toyota and Mercedes would all be thrilled if everyone changed their oil every 9K or 10K miles. Sorry I have to disagree with you on this one. The car would probably make it through the Warranty period if you did this. And I am sure those Mercedes engineers have built their cards to do just that.
But soon after the warranty expires I don't like your odds.
The owner's manual for the Crossfire says every 7,500 miles because they are very confident the car would make it through the warranty period if the oil was changed at that interval.
Beyond the warranty period they could care less. They want the car to die at that point and then sell you a new one.
I completely agree that every 3K miles is ridiculous and is a rip-off. You are spot on there. But 9K miles per oil change is a bridge too far for me.
Maybe King Solomon had it right? Split the difference:
(3,000 miles + 7,500 miles) / 2 = 5,250 miles.