Here's the tricky part for me - here in Pittsburgh, we'll get some 0 degree days, but we'll also get 50 degree days in the winter - but it usually hovers right around freezing. I have the same concerns about my snowblowers and plow tractors. A typical excerpt from a Briggs, Tecumseh, or Kohler manual: [In temp above 32, use SAE30 - using multi-visc like 10w30 and 10w40 can cause overheating, increased consumption, and engine failure. Below 32 degrees, use 10w or 5w30 - the use of SAE30 can cause hard starting, poor oil flow, and engine failure.] So I'm kinda 'damned if you do, damned if you don't' with oil weights.

 

I hear ya...had the same issues myself...what to use and when. I have an uncle that is a retired engineer for Briggs and Straton Corp so a number of years back when syn oil was hitting the market I ask him the same questions you proposed. He did some researchand sent me some info about the qualities of syn oil vs. dino oil. For most common ordinary use a dino oil is perfect and if changed regularly would work well for most people. As we tried to get more from smaller engines we found a need for better oil stability in a thinner (lower weight) lube that will lubricate tighter tolerances.
This is where the syn oil comes into play. The references in the manuals are based on dino type oils, in fact many newer manuals such as the one that came with my Areins snow blower and lawn mower now state the same but there is also an exclusion if you use syn oil. A multigrade full syn oil such as a 5w-30 will be suitable in all temp ranges from -20 to 100 degrees. The mfgrs are just now catching up on there printed materials with the popularity of syn oils. Every major engine mfgr has now come out and stated that tests have proven there is less engine wear with syn oils and they are more slippery to gas mileage improves and syn oils can be made thinner for todays higher reving engines that allows the lube to get into smaller spaces. For grama and grandpa's daily driver dino oils are just fine but once you get into any performance type of engine the syn is proven to be superior. With the price of syn oil coming down and dino oil going up it is becoming a tough choice whether to save a couple bucks or spend a couple bucks to make your engine last a little longer. With my UTV running at high RPM's on a regular basis I will spend the extra to help protect it, to damn expensive to replace it. I believe if you actually read the latest specs for your engine mfgr you will find updated oil specs pertaining to syn oils. Thanks for your thought on this topic!!

 

What is the oil capacity