[oilman]

Full synthetic is not used only in race engines, it's used to get the best protection in any vehicle. All new and newish BMWs, Audis etc use fully synthetic oils and you find they will often easily go past 200000 miles with no problems at all (one at home is on 275k and drives like new)

Synthetic oil is not thin, it's whatever grade you buy it in. If you buy a synthetic 5w-40 it will be nice and thin when cold so you get good cold start protection, but the same viscosity as a bog standard 15w-40 mineral or semi oil when it's up to temperature.

Synthetic oils burn off slower than mineral or semi oils as the synthetic oils are more stable and are made up of molecules that are all the same size. The molecules in mineral and semi oils are all random sizes and it means that the smaller molecules evaporate off and get burnt when the oil is hot, and then leave behind the larger heavier moleules that flow slowly, so the oil just doesn't lubricate properly after a fairly short period of time.

It's up to you what you use.