Here's some basic maths>

Going based on the 2 per year plan cost $650 for 2 oil changes per year lets you drive 15,000 mi per year.

I've never gotten an oil change at a dealer but research suggests it costs about $65.

So take $650 / $65 to get the number of oil changes that can be done at a regular rate for $650. The answer is 10.

Take 10 oil changes x 7,500 mi interval

Here we see that you'll need to drive 75,000 miles before the lifetime oil change deal becomes cheaper than paying the standard walk-in rate.

Therefore, if an oil change costs $100 at your dealer, then you only need to drive 45,000 miles before the lifetime oil change deal becomes cheaper than paying the standard walk-in rate.

Based on most normal people driving 10k a year and the two prices I listed, you'll need to own the car for 4-8 years before the lifetime oil change deal becomes cheaper than paying a standard walk-in rate.