Some vehicles can be an investment.... however the Focus is most likely not one of them. However what was the price tag for the RS 500 new and what would some one pay for it in mint condition? Their are many cars that can be an investment, but most of those are not made by US car companies.
What is the thought of thew remote dual oil systems like Amsoil has that uses a regular filter and then a "super" filter that slowly filters out the even finer particles? I know their have been concerns that the oil coolers for our motors are not needed and can cause for a longer delay in getting oil pressure. I am guessing the same thing applies to this. But would provide better filtering, perhaps only a need if you have a turbo that making your oil more dirty?