I just purchased a new Poulan push mower with the Brigs & Stratton 5.0 motor. I really like it. Has plenty of power for what I need it for and engine runs quiet in comparison to my old mower. It came with 30 weight Poulan branded oil. The chart indicates you can use synthetic 10 W 30 for all temp ranges but only 30 wt from a certain temp up to 100 degrees. What do most of you guys use? Also, I just got the mower and have only used it once. I will probably only have to mow 2-3 more times before winter sets in, maybe 4. Does the oil get degraded just from sitting in the mower in a cold garage all winter and need changed in the spring even if I’ve only used it 3-4 times prior to winter?