what are you blower guys using for oil?

The particular supercharger itself isn't the reason why synthetic oil isn't recommended with a blown application, it's what happens with your engine that throws a wrench into things. Forced induction engines are more susceptible to blow by because of their elevated crank case pressures. Synthetic oil tends to get by the rings, seals, PCV valve, etc that much easier than conventional oil and a lot of users end up with all kinds of problems because of it. For one, you've got excessive consumption issues which are tough enough to control as it is with a Modular engine to have now worry about amplifying the problem. Secondly, since more of it is getting by, it more readily contaminates the intake components (Air inlet ducting, mass air sensor, air charge temperature sensor, throttle body, intake manifold, bypass valve, intercooler) making not only a real mess, but it leads to a less efficient after cooling of the air charge and can even lead to a reduction in fuel octane levels.

If someone insisted on not listening to reason and chose to continue running synthetic oil in their engine, I'd be very thorough about monitoring consumption levels and possible contamination of the system on a regular basis. CONSIDER OIL SEPARATORS MANDATORY!!!