It's hard to argue that after 11 hours and 4 months that the lubricating properties or contamination of the oil requires that it be changed. I too often face a similar situation where I've put less than 15 hrs on an engine in a season, and I'm never quite sure when my season is over, as we frequently get some 90F days in October here in northern California.
My household has 2 dirt bikes, 8 cars and a boat. Four of the cars are used infrequently (as are the boat and dirt bikes), and are all on battery tenders. It seemed that my infrequently-used vehicles were getting oil changes more often than necessary, as what came out of the crankcase was almost as clean (eye-balling) as what I was putting in. But I believed the theories about acidification and removal of contaminants on a periodic basis, so I changed everything that was infrequently used annually, with synthetic oil, thinking this was cheap insurance.
About 8 months ago I heard about and purchased an oil tester from
www.lubricheck.com. It's a small device into which you put a couple of drops from the end of the dipstick, and it performed some kind of analysis - I suspect pH, and perhaps a refraction for particulates. I have 2 cars with "oil life monitors"; both of which I believe are algorithms based on time, load, temp, etc, not an actual analysis of the oil. Much to my surprise, there was a pretty good correlation between the oil life monitors on my GM car from 2001, my Lexus from 2012, and the lubricheck device. Enough that I now use this device to dictate when the oil should be changed on the dirt bikes, classic cars and the boat. I think this device has probably paid for itself in deferring unnecessary oil changes.
Of course, for the cars that are used regularly, I follow the maintenance schedule, or the oil life monitor, but having an independent analysis with this device allowed me to extend the 3-months or 3,000 mile traditional auto oil change interval to > 6 months on my older, but daily-driven cars, and not fear for the well-being of the internals of my classic cars, boat and dirt bikes.
I just checked their website, and although the price has increased from when I bought mine (they want $50 today, where I swear I paid $40 for it back in January), I have had a positive experience. With synthetic oil running >$5-6/qt, it will pay for itself in just a couple of deferred oil changes (or in my case, one, as the crankcase in my 1955 Jaguar holds 12.5 quarts!), and it gives me peace-of-mind for all those engines that are infrequently used.