Up to you. Good synthetics are generally better than normal oil, but they cost more, and normal oil is often "good enough". So it becomes a numbers game (i.e. do the savings/benefits outweigh the extra costs, in your situation).
My personal feelings are that synthetics are "worth it", and can pay for themselves with both longer oil change intervals (and therefore fewer oil changes, albeit each oil change being more costly), as well as slightly better gas mileage (which can save a small amount of money at the pump). But this clearly seems to be a YMMV thing (i.e. each car is different as to how much synthetics help, and how much extra it costs to use them over normal dino oil).
Originally Posted by 99Corolla
I wouldn't. According to the testing done over on BITOG (The "Bob Is the Oil Guy" forums), "Royal Purple" seems to mostly make synthetic oils good for racing usage, but that aren't very well optimized for more normal "street use".
What that means is that Royal Purple appears to give very good performance SHORT TERM, but then (unlike most good synthetics) doesn't seem to hold up very well. And to add insult to injury, Royal Purple is also more costly than many other synthetics (that work better in a "street vehicle") as well.
Personally, I'm a big fan of some of the top of the line Amsoil oils (I use both their 0w30 and their 0w20 oil, and they have both worked very well for me. OTOH I did go to the trouble of getting myself registered as an Amsoil dealer (in part, so that I could get their products at a discount for both me and my friends), so I admit I'm a little biased.
if it were me, I would start with a grill block or warm air intake. those are cheap and relatively easy to do. the spark plugs I think may depend on how long you have had the car and the mileage. the oil I have heard doing better FE but you change it out every 3 months so you would really have to see if you would save enough to pay for the better oil (in my opinion). some do let you go longer intervals between changes (that is definitely a plus).
the reground kit seems a little strange. you can go to your local car audio store and get most of that stuff (may not be much cheaper). I can't say for sure about that one.
still say start with a grill block. better aero and faster warm ups on the engine.
Be the change you wish to see in the world
The re-grounding kit, is more for high performance cars, racing, modified electrical systems etc. I would say re-grounding your car would only become necessary on your car if it had at least 15 years on it or you are doing some mods to it that may require some extra grounding to the battery. Even then I doubt it'd make much difference to your MPG, a slight performance and that's all. Usually you can get the wires for cheap and just use the factory grounding spots.
As far as spark plugs go. Your NGK V-Power plugs are going to be the best ones for your car, and MPG.
Royal Purple is something you couldn't get me to touch even in a race car. AMSoil is a great pick, also Penzoil Platinum is also a really great syn oil to use, but expensive. For an inexpensive oil I personally use Havoline standard 10-30 to 5-30 oils with Purolator oil filters ever 3000 miles.