Also, Jim told me the fan clutch was shot. I've had the new one sitting on the shelf for probably six months, and so am glad that wasn't wasted money. I'm really looking forward to seeing how the new fan/clutch combo works. He says it's a much better fan design than the original. Even pulling out of the shop, I could hear a difference.
As I think I've mentioned before, most of the time when I talk with Jim I learn something useful. Yesterday after he finished installing the fan and clutch, we were talking about my daily driver, which has been in his shop for over a month now (!), for a clutch replacement and some other stuff. He's had a heck of a time getting the right clutch slave cylinder, and has had to take it apart multiple times now. The latest iteration is he found what he thinks (and hopes) is the correct one, sourced from an eBay seller in Australia. That doesn't surprise me, as I've searched for other parts for that car and found incorrect listings, even though they had the same part number. It's a particular problem with the HHR SS, which was a comparatively low production vehicle, and many of the parts differ from the regular HHRs.
Anyway, we were talking about port injection vs direct injection (a '96 Suburban is the former, and my '08 HHR is the latter) and the importance of fuel choice in a DI motor. I always run premium in the HHR, which is recommended but not required. This then led to a conversation about fuel type in the Subdivision. He surprised me by saying that I'd be much better off using premium while towing, due to the higher potential for detonation under heavy load, which shortens the life of the motor. More expensive, of course, but well worth it. He said to save some money, a 50/50 mix of regular and premium would be enough to get the octane up to ~90, which would do the trick. FWIW, he also owns a gas station on the premises, but I don't buy my gas there. But he seems to be knowledgeable about fuel.
I'm going to give it a try. While I'm not happy about the higher fuel cost, his explanation made sense to me. Until now, I've used the cheapest regular I could find. At the first fill up on Monday's trip, I'll switch to premium. I'm wondering if it will help with gas mileage. We'll see.