SkyKC, All manufacturers I have seen are specifying 0W-XX or 5W-XX oils now. Honda, Ferrari, Ford, Mercedes, Porsche, and others specify a 0 or 5W-XX oil to mention a few. These are appropriate for all engines of all ages of all levels of wear. This second number is the only thing that may change with an older, lose or worn engine. I have heard that oils labeled for RACING ONLY is not usable for every day driving. Often these have more additives that are toxic to your catalytic converters and the environment. These oils generally do not have detergents. These are very important for your engine unless you plan on taking it apart every few weeks and cleaning every single surface. Motul 300V says its for racing cars not sure if its for RACING ONLY. Try German Castrol 5w-40 you can buy it from Harold from Performancelub (i think thats the name) its a good oil. I have recently put German Castrol 0w-30 in my WRX and it seems to love it and the engine is so quite. I guess you have to experiment to find the correct oil then stick with it.
If your still confused and feel like learning more on oils either goto http://63.240.161.99/motoroil/index.html (HIGHLY RECOMMEND reading this although a little long but you can skip some chapters)
http://www.bobistheoilguy.com