Oil Change - synthetic oil

I have always changed all my convention oil at 3-4K miles. And all my synthetic oil at 4-5k miles. If you were only changing the oil at longer intervals then no wonder you needed an engine early on. Oil changes (even synthetic) ar cheap compared to an engine replacement, especially if you are on the road. I just sold an 01 Explorer with 200k on the original engine and trans, basically everything. It got regular fluid changes of all fluids. My sons 98 Mercedes has 180k on it. Original trans and engine. Although MB says 12k mikes oil changes i and the previous owner do it every 5k. My daughter 01 Jeep Grand Cherokee with the 4.0L has 190k and has had 3k mike oil changes, not sure about the previous owner. But when I did the rear main seal the inside of the oil pan and motor were very clean.
Preventive maintenance goes a long way! We spend a lot of money on vehicles why not spend a little in comparison to properly maintain them.