So the last few cars i've owned, i've always, after a moderate amount of miles, switched out both the engine oil and the transmission oil for full synthetic...anyone done this? If not, is it a good idea? Your opinions please.

Thanks in advance.

This has been discussed so searching XOC will surely get you as much info as you want. My understanding is that today's lubricants all have to meet certain standards and today's engines have better seals and so on, so it doesn't matter whether you use synthetic or standard oil or when you put it in.

I switched to mobile 1 at around 50 thousand miles. It promptly developed a leak at the oil pressure sending unit. Easy fix, no other leaks, and it may have been just a coincidence.