Costco gas is Top-Tier, so would you still recommend a mainstream gas station instead of Costco?

"Top Tier" is not a legally recognized product designation in the most northern states, but I understand what it is designating. Long explanation for that beyond the scope of this thread. IMHO when fuel is less expensive, there is a reason for it.

In reality, what Costco (Kirkland) did was increase its additives in 2014 to obtain that designation. Detergent is available from many suppliers, if you bulk up on the content from a cheaper source is it really the equivalent of a similar fuel with better quality additives?

All I was trying to pint out is, Premium is determined by Octane, the stock H3 is factory set to burn 87, anything more is just draining your wallet at a faster pace for nothing in return. It is you wallet, burn it how you like. :cool:

Good to know. I went with Exxon regular after adding Techron. The price difference was just $3.00 total for 20 gallons compared to Costco. Did seem to perform well driving and idling has slightly improved.

So it looks like the rubber part of a motor mount is cracked. I attached pictures to show this. Having them replaced this week and should hopefully fix the rough idle/vibration.

So replacing the mounts did improve the idling, but it is still not 100%. More often it is better, but at some times and after driving a bit, there is still a noticeable rough idle/vibration. I feel it mostly in the steering wheel.

Also, something new happening is that on start up, this is pretty difficult to explain, it kind of shimmys or wobbles (left to right motion). It lasts for a second or two and goes away.