I know that for the GTM the Porsche G50 gets rolled over to make it work.

There is a vent at the top of the gear box that I assume will get put where the drain hole is and the vent hole now becomes the drain hole.. The fill hole is on the side of the gear box and when you roll the gear box upside down to put it in the GTM how do you check the oil level now that the hole is much higher that it was??

I see that the G50 holds 4 Qts of API Class GL5 75/90 Synthetic. I see there are several different brands, what is the best one to use??

Thanks
Mike