There are lots of tests that PROVE that synthetic oils are better than dino. On top of that, there are great synthetics, and mediocre synthetics. An FYI, in all tests I have ever seen, Amsoil produced the best oil, period.

 

Mobil 1 Synthetic all its life.

 

Synthetic oil was originally developed to handle the heat of jet plane engines, in which dino oil would break down and lose lubricity. Synthetic oil has extreme cold flow characteristics where dino oil will gell. It has greater ability to lubricate under load and pressure, and true synthetic oil like Mobil and Amsoil--not the blended oils like Syntec and others--will not turn to sludge and varnish in your engine, since it contanins no parafin as conventional oil does. Consider it the cheapest best insurance you can buy for your engine.

 

Don't buy in to all the synthetic hype, unless you are running extended drain intervals it really isn't worth the extra cost. Use a quality conventional and you engine will be just fine.

Mixing different brands of oil and synthetics with conventionals together is just fine, no harm will be done.

 

Synthetics have several advantages. Whereas petroleum based oils are single weight (30, 20, 10), synthetics are multigrade right of the bat. Petrol based oils use additives to modify the viscosity--ie converting it to 10w30. The flash point is also an issue. The synthetics are better lubricating when you first start the car. The synthetics age better.

Unfortunately, the contaminats from internal combustion, will still produce sludge. Detergents are added to oils and these keep improving. 3000 mile intervals are definitively excessive unless you are in a severe climate (see your manual). You may know of Car Talk, the Mallozi brothers. They were running one of their cars without ever changing its oil. I haven't heard on the car for a while, but at least after 2 years it was still going. An oil analysis is inexpensive and it can tell you if your oil is doing ok. It can tell you if the oil viscosity has dropped to unacceptable and how much life it has left.

That being said, you have a high performance engine in your car that Rev's up to 8-9000. Oil is not the most expensive part of the maintenance. I use synthetics and usually go 5000 miles between intervals. I just bought the S2000 so my experience with it is minimal. However, I can look back at cars including my 1996 Cobra with 127,000 miles. Engine is intact--factory specs (as is everything else on it). When I need a HP fix it comes out. It is a convertible.

Current engine oils are dramatically better than anything from 10 years ago. SAE has a lot of info on it. Howver, you can never go wrong with the recommendations of the car manufacturer.

 

I was wondering, and maybe road rage can address this, Honda does not recommend using synthetics during the break-in period because it does not allow for the pistons etc to set (read-wear in). If that is so, are they not admitting that synthetics produce less wear than mineral oils? Honda is not the only manufacturer to state this. I have always used synthetics in aluminium engines, but I did not think there was that great an advantage. Now I am thinking there may be.

Also, what about the molybdenum? is there any advantage to adding it periodically?