Difference with high octane?

@VTCAL

I think you quoted yourself, LOL...

Anyway, I take incredibly good care of my truck, and had never had this type of issue before; I had just had the water pump replaced and thought I was in the clear. I was also of the incorrect assumption that a well-maintained 2TR-FE wouldn't be overheating at less than 160K miles when these engines routinely made it past 300K without an issue, and certainly not that my head gasket had blown...

 

I have historically gotten my oil changed every 5K miles, but there was a period of time between probably 84K miles and maybe 115K miles (June 2018 through the summer of 2020) when I went 6K-8K miles between oil changes. After the truck started "using" oil, I went back to 5K...

So, the head gasket was replaced just shy of 158K if I remember correctly, and as a matter of course the oil had to be changed; I provided 10 quarts of Mobil 1 Full Synthetic High Mileage Formula when I left it with the dealer. My truck ran better, but the gas mileage was still crap...

I have Aspergers Syndrome and am very OCD, and felt a little uneasy about going to 155K after the engine had been partially torn down, so I had Pete change the oil at 160K. Just for grins, I had him put in 0W20 high mileage just to see what would happen...

Not only was my truck no longer "using" oil, but my gas mileage drastically improved! As long as I don't idle a lot, I see 15-17 around town, and 18+ on the highway. My highest average MPG since the head gasket job was 23 MPG, and a couple months ago, I averaged 17 MPG pulling a 16-foot trailer!

 

In either 2020 or 2021, I wasn't paying attention at a Sheetz in Carlisle and put 89 in the truck instead of 87; I averaged 22 MPG with the A/C cranked driving home, but now gas is too damn expensive so I only run regular. Keep in mind this was after the truck started "using" oil, but before the head gasket totally blew...

 

I used 87 once in the 2012 I used to own, and it knocked heading up the mountain to get home. No more. Not at these compression ratios. Flat roads are okay with no load. However, put a heavy load whether it’s hauling or towing up a steep grade, fuck that. Top tier.