I would say that HDEO would be a better choice. So, there are no drawbacks.
And, if you have a supply, stick with small engine oil.
I also like Ford's take on API. Their approved list of HDEO's is an excellent start. But, you can't go wrong with the small engine oils from VP, Briggs, Honda, Amsoil...
We have large lawns around here.... notice plenty of neighbor engine failures with mowers/generators... all using various PCMO's. One thing I noticed during disassembly are 'clean engines' with too much wear/tear internally. I don't recommend a PCMO in a small engine, lawn mower, generator, or motorcycle.
Stick with synthetics, HDEO's, and small engine oils when possible. Obviously, a full sump is better than empty. Use what you got, or can get, to top off, if you need to finish the job now. Shop smarter for those tough little engines.
To maximize the performance of your Toro lawn mower, we highly recommend using Toro full synthetic SAE30/10W30 oil, which has been specifically formulated for best results.
VP SAE 30/10W-30 synthetic 4 cycle engine oil delivers superior thermal resistance, protection, & lubrication for small engines in portable outdoor equipment.
100% Synthetic SAE 5W-30 for use In all air cooled 4-cycle engines. 32 Oz. bottle. SAE 5W-30 Synthetic Engine Oil 32 oz. bottle Formulated for air cooled, 4 cycle engines in outdoor power equipment For use in all air-cooled 4-cycle engines Warranty approved for Briggs & Stratton® engines...
And, obviously, I won't leave out the non-neutered oils from Redline, HPL, Royalpurple, MPT... either.
High-Performance Motor Oil
HIGH PERFORMANCE ENGINE OIL (WITH SYNERLEC®) HPS is recommended for use in gasoline and diesel automotive, commercial fleet and stationary industrial
If you have a normal screw on filter, oversized options are available. You'll get a few more ounces of oil capacity/cooling/filtration/flow....