I used 30 wt. for years with no real problems until I started up my Beetle one day at work when it was about 5 degrees and pulled on to Hwy. 27 about 10 seconds later. I blew out two quarts of oil in the 13 miles between work and home. When I stopped to add oil, it took forever. At near 0, 30 wt flows about like peanut butter! After the weather warmed up, I cleaned all the oil off the engine and tried to find the leak, figuring it was the oil cooler . . . but there were no leaks. Ever since then I've been taking David's advice and running 20-50.
