Chain and bar oil is what I have used for years successfully. To access the chain for checking the adjustment, there is an 8" or 10" through bolt that goes from right to left (or left to right) on the cover. You take that bolt loose, and the cover will lift up. It is somewhat of a pain to get it back through into the other side, but it is doable if you have patience. To adjust the chain there are two bolts and nuts that need to be loosened on the bottom side of the metal fixture that slide up and down. I would leave them just slightly loose, and then tap the steel plate with a hammer till I had the desired setting of not too loose or too tight. If you hit a large object that breaks the shear bolt and brings the snowblower to a sudden stop, there is a good chance of damaging the chain to the point that it will be bent and become trash. This is why you should check the driveway before the snow for any errant rocks, pieces of wood, or newspapers that are going to ruin your day. I speak from experience and any of those items can cause expensive damage that will take a lot of time and effort to repair. Also, make sure that if you break a shear pin you have your augers properly "clocked" as the decal on the inside of the snowblower on the right side shows.