What type of Subaru did you have before? A 2001 Outback? I'm not planning on doing any towing, which I noticed was something you used your Subie for, but it's good to know about any sort of issues before I pull the trigger. Would upgrading to an aftermarket header and/or wrapping the stock exhaust solve any of those problems? Also, what length of road trips are you talking about (e.g. driving for multiple hours, climbing big grades) when you refer to your past experiences?
Sorry for the thread hijack, btw!
2001 Legacy GT Limited 5spd MT 2.5L - Its an identical car to the OB in every way except the taller suspension, they were rated the same for towing, they have the same exact running gear they even sport the same exact hitch and mounting gear. In many ways the sedan body is just stiffer and stronger than the more flexy OB wagon body. I bought my mom a 2010 legacy before we bought our 2010 OB even today the Legacy and the OB are identical platforms regarding engine, transmission, cooling system yep even the hitch mounting is identical between the two still. Around 2007 Subaru stopped rating the Legacy and the Impreza for towing capacity but they rate the more expensive models on the same platform ie the OB, Forester and the XV simply as a marketing ploy to drive more people to the higher profit margin model given they think they are getting more car when in reality the Impreza and the Legacy offer the same ability as the XV, Forester or OB etc and just are not getting published marketing data for tow ratings. All the auto makers do this today, RAV4 vs Corrolla, CRV vs Civic, Ford Escape vs Ford Focus- in reality they all have the same towing and load capacity given they are all the same machines regarding engines, transmissions and cooling etc.
Yes we towed but we also had lots of trailer free trips where nearly every trip I found some type of combo be it outside temps + head wind or speed etc where I saw a bump in temps. The second that generic needle moves from center your overheated so anytime ours started to gravitate beyond normal I was in full temp management mode till the needle settled back to normal. 180,000 miles and 12yrs of trips all over the west coast both with trailers and sans trailers only reason we replaced it was for the larger wider 2010 OB given the old 2001 was still 100% heck its last major road trip we did 2500 miles mid summer at 170,000 mile mark zero issues except yep found our limits on cooling outside of LA headed East on the 10 with nothing but a skinny roof box on the lid. 72mph temp would start to rise, back it down to 65mph and it was perfectly happy. It didn't help that we had a 15mph head wind blowing 98degree desert heat at us and the 10 headed East out of LA has a little bit of an incline for a while.
Having said that anytime the outside temps were under 80 degrees I could push the car hard and be pretty safe not to see a temp spike. But its hard to find a CA summer trip where you don't cross 100 degree weather at some point be it Fresno headed to Kings Canyon, LA Grapevine or passing through Redding CA in 115 temps while headed to Oregon or Washington.
Running synthetic motor oil helped some seemed to increase the tolerance just slightly for the hot temps over standard motor oils. So in the summers I ran synthetic and in the winter I ran standard, mainly given standard oil had the heater warmed up in half the time than it took with synthetic in the car.
The 2010 I found I can pack it heavier, and run harder in hotter outside temps without any cooling system overload issues the dramatically improved air flow through the front end increasing the cooling systems efficiency and yes the greatly improved exhaust routing and exhaust port sizing has made a big difference also. However cold starts the 2010 2.5 sounds like a MAC truck thanks to the greatly improved exhaust porting at least till its warm then its quiet again.