Passat using oil?

You might laugh but I'm still running the 1995 Volkswagen Passat VR6 I have owned for the last 10 years. I have driven many late-model cars, but still enjoy the solid feel and confident road holding of the old Passat. As it has only done 175,000km and my question is what engine oil would you recommend and would it need to be "thicker" now the engine is 20 years old? It doesn't use oil when driven locally, but it will use 500ml per 1000km at freeway speeds. It has been very reliable, starting & performing well, with no problems.