After failing to obtain Honda's absurdly thin NEXT oil, I settled for the next best thing, Honda's Green oil.
Genuine Honda Hybrid Engine Oil 4 ltr (Honda Green Oil) [08232P99S4LHE] - £40.89 : Buy Genuine Honda Parts, Honda Car Parts & Honda Spare Parts Online
Viscosity at 100c / 40c (cSt):
Mobile One 0w20 - 8.7 / 44.8
Ravenol 0w16 - 7.2 / 38.4
Honda Green Oil - 8.2 / 32.1
Honda NEXT oil - 5.1 / 20.8 (Blackstone Analysis)
Green Oil is much thinner than 0w16 when cold, but closer to a 0w20 when warm.
Yesterday I fixed a small oil leak, did an early oil change (6000mi), and sent a sample of the Mobile One 0w20 I'd been using since I bought the car off to Blackstone for analysis. I'll do an analysis of the Green Oil at the same miles, to get as close to an apples-to-apples as possible.
Subjective experience: Insights have very clattery valvetrains when cold, sounding a lot like an older VW TDI to my ear. When warm the noise mostly goes away and it becomes a very quiet engine. After changing the oil and starting it up, I noticed a very distinct reduction in the noise of a cold engine after about 10-15 seconds.
Over the past 24 hours I've driven the car about 150 miles, and something unexpected has happened - I'm having the damndest time getting it to warm up now. Temperature outside is ~25F. The thermostat starts to open at ~184F, and I'm finding that with no changes to my grille block, I'm now hovering in the 175-180 range when cruising, even when I turn the heat off. It warms right up when I start climbing a hill, but then quickly cools back off once I'm going down the other side. So, I'm going to need to adjust my grille block.
Another thing, it's a bit early but I'm guessing my gas mileage is going to go up a bit. I last drove the car Tuesday, and temperatures were about the same. I averaged 72mpg on my way to Burlington, which is about 30 miles, and 68 on my way back, letting the car sit and cool off in between. I'm not saying the oil is solely or even largely responsible for any improvements I'm seeing, as conditions are slightly different (mostly there's slush on the road now after a snowstorm), and the sample size of a few shorter trips is pretty small, but I snapped this pic on my way to Burlington earlier:
Again, ~25F, roads are mostly clear but wet, with patches of slush here and there.
I'll update this in another 6,000 miles with Blackstone's findings, compared side by side.