While reading up on the specifications of the 0W-30 and 0W-40 versions of these oils, I see that they are PAO HDEOs. The specifications for the small engines I have (Honda GX610, B&S 7.5 hp, etc) call for the use of SAE 30 engine oil during the summer. Using Esso Universal HD as an example, the 40/100°C viscosities are 100/11.9 cSt for the Universal HD SAE 30 compared with 69/12.2 cSt for the XD-3 Extra 0W-30. Comparing the viscosity indexes, the SAE 30 is 105 vs 176 for the 0W-30. The 0W-30's pour point is -45°C compared to -24°C for the SAE 30. This would suggest to me that that the 0W-30 could be used year-round in the Honda engine. However, the BITOG "High Detergent" oil suitable for snowblower thread seems to indicate that 0W-30 oils are unsuitable for temperatures above freezing. I've repowered my 782 Cub Cadet tractor with the 18 hp Honda engine and use it year-round for with the snow-thrower and mower deck. Is there a good reason why Esso XD-3 Extra 0W-30 could not be used year-round in place of SAE 30?