Bump for a very long thread!
Until recently I only used M1 5w30 in my 8 year-old Briggs push mower. No smoking, or any other issues.
However, at the beginning of summer I tried Pennzoil 30 weight. Price was right, so I thought I would save a little cash.
But, there is a problem: Now with every start the mower smokes for a minute or two, and there is definitely more noxiousness to the exhaust.
The mower is very well maintained, so I am perplexed as to what could have caused this, other than the different oil (I really like Pennzoil products, so I'm not slamming Pennzoil).
The fuel is fresh, spark plug is fine, filter is in great shape...strange.
Anyone else have a similar story?
I will try some Valvoline Synpower full synthetic I have left over, to see if the issue improves.