Short-changed on oil

I READ that all dealers change the engine oil at the first service as a matter of course, but my experience is quite the reverse. When I took my Mitsubishi Magna for its first service, I was told they don't worry about it. I had it changed anyway. Because I do low Ks, I change the oil myself at 7500km between service intervals by sucking it out through the dipstick. It's all over in 30 minutes. I change the oil filter at the 15,000km dealer service.