So you're saying he should use 10W?

As for the wrench, I found out the hard way that (when you can't use your hand because someone put it on too tight) that the end cap wrenches are only compatible with the filter that it was designed for. If you want a general purpose filter wrench, get the one that looks like a looped nylon (like a seat belt) strap connected to a squared rod with a small hole through it. This wrench wrappes around the stubborn filter and you wind up the slack onto the rod. Then you stick a screwdriver through the hole and twist. It's also good because it allows you to get into tight spaces with it.