There's nothing "cheap" with that at all, other than the price. I routinely run my cars waaaay over 100,000 miles using exactly what you listed there, and no other miracle crap additives at all. You'll be fine with that.

As for the oil pressure reading, swapping in a mechanical gauge temporarily will enable you to get a "second opinion" to tell you if the original sending unit is going bad, or if you really do have a weird high-pressure problem there.

I wouldn't normally hook up a tester gauge to the existing sending unit.... Actually this may help you decide whether the sending unit or the dash is bad. First I would check to see that I really don't have goofy oil pressures.

Lol synthetic makes you leak oil, how do you figure?

The extra detergent properties of synthetic oils tend to remove the existing varnish or buildup (for lack of a better word) that previous organic oil did not, which tends to open leaks in worn seals that up to that point had not been leaking.

In short, switching to synthetic at an early point in the engine's life may help minimize wear over the long haul, but switching to synthetic much later on will simply enable it to leak out through, and around, the wear that has already taken place.