I got my car onto fully synthtic Mobil 1 at 1000miles,
if you want ultimate engine protection use fully synthetic earlier rather than later. Do not go straight from mineral to synthetic use part synthetic for a few k first, Simple and easy.

I don't think you really need to go part synthetic. No matter how well you drain the regular oil, you'll still have quite a bit left in the engine. Just add full synthetic to it and it will become part synthetic automatically :)

Start with Mobil1 early cause my 96 Pro with 80000km done on GTX didn't liked the switch to Mobil1 even with a engine flush product between.
Now I'm at 149000km(93 125miles) and I have to add 3 extra liter between oil change!!!
So I'm going back to GTX...

As for Redline, it's the best I tried(MTL 70w80), specially in winter... but too pricey.
I'll try the Castrol Synth Gear oil next.