I looked at the Briggs manual for this engine and it indicates Synthetic 5w-30 may be used for all temperatures. I use this tractor in the winter quite a bit which was one reason I wanted to stick with 5w-30. Please see attachment from manual. Sorry the scan is not better.
Perhaps in the hot weather I should be using 10w-40 as someone recommended.:confused:
More important than the weight being 5w30....make sure the API letter starts with a C ...do not use oil that starts with an S!!! If you put regular car oil in it (API S) ,get it out ASAP...it isnt meant for diesels,and doesnt have the durability needed to protect your diesel engine.This is what matters...and 5w40 full synthetic oil outperforms 5w30,and is suitable for all climates,also much more readily available than 5w30 C oil....
FYI Kohler Command oil is 10w30 diesel oil,and most small engine shops sell it,look at the API label first letter is a C,so its good to use in the diesel.It isnt synthetic though.