With this 1st run of M1 10W-30 High Mileage oil:
For 1st 1500 or so miles, every startup was free of the "phart" sound that I've been told is from the starter disengaging. I assume more resistance to cranking increases the chance of the phart sound. After around 1500 miles, it was back to it's old farting ways...don't know why but I'm sad that the magic is gone.
Gas mileage so far seems to be at least as good as it was with M1 0W-40 which has been one of the best for me of all oils I've tried. I haven't analyzed all the MPG data yet.
Engine does seem to rev more easily with this oil. I've mostly been driving gently though so that's all I can say in terms of performance. Of course there is the occasional petal to the metal to pass slow people.
Before I kept getting soft deposits sitting on the lower parts of the dipstick. I'd wipe them off and next time I'd check, more were there. I also saw them early in this current fill but they have stopped appearing since then which may mean that all the loose soft deposits are nearing their end ("clean-up" is nearing its end, at least for that particular type of deposit).
I pulled a PCV hose to make sure it had an oil layer in it to verify PCV system functioning...it did and I plan to keep it that way and keep it free of deposits in the future. It's going to take vigilance to keep it that way.
Overall, I'm pleased with how things are going. Will change the oil early; between 3000 and 3500 miles. Not sure what will come next but likely the same M1 10W-30 HM, especially with winter on its way.
