Snowblowers – Fixing Blades Hitting Sides Issue

Use the 10w-30.

If you store the blower in a warm place then you need do nothing further. If you store the blower in a cold place (around -20°C) then you should replace the 10w-30 with 5w-30 as soon as practicable. In the meanwhile, double or triple the warm-up period before engaging any load.

The first number is the viscosity as tested under cold conditions. The different oils are tested at cold temperatures particular to each viscosity. See the chart on this page. The second number is the viscosity at typical engine operating temperature (around 100°C).

If the first number is too high, the engine will not get enough oil flow when very cold. (Also it may be hard to start.) If the second number is too low, the oil will not protect the bearings enough when hot.

In your case, the 10w-30 may cause some excess wear for the first few minutes of operation if you store the blower outside, but the 5w-20 certainly won't provide enough protection once the engine is warmed up.

My Craftsman 3/21 single-stage, 2-stoke snow-blower now works perfectly and discharges snow from chute as expected/desired. Thanks to everyone that helped me solve this HI/DIY problem!!!

Corrective steps toward problem-resolution:

1. Replaced drive-belt (specification was 35"; my old one had stretched out by over an inch)
2. Replaced auger-blades (hard rubber) with new ones. The old ones were worn-out and were not (almost) sweeping past the backboard near the chute. The recommended gap is less than 1/4 inch. My old blade had a gap of almost 3/4 inch
3. Sprayed snow/ice repellent near the neck of the chute to prevent ice build-up when dealing with wet-snow (as was the case today in Chicago).

BTW, I took this DIY opportunity to replace all screws & aluminum rivets with appropriate stainless steel nuts/bolts/washers. It costed me an additional $6; however, I thought that it will save me a lot of time when it comes time to do maintenance on my snowblower some time in the future ... especially since the screws get rusted quickly as snowblowers are mostly/often used in wet conditions and we (at least I) often do not take the time/trouble of wiping the snow-blower after using it (since it is too cold outside).