In the online manual for the 6039 concerning end of year maintenance, it states to use spray vegetable oil (Spam or eqivalent) on the fan units. On my blower fan (on left side of unit) it starts up with a high squeek/squeel. So I used Pam spray on the exposed end of the spindle/shaft in the squirrel cage. It stopped the high pitched noise on the following stove start up. But it reappeared on the next start up after the weekly cleaning. Here is my question. Why can't I use WD-40 or 3 in 1 Oil on the spindle/shaft??? Any ideas?