The service manager copied a 4-page document for me. It's apparently from the GM web site that the mechanics use to get their procedures. The document is listed as being from the 2018 Trax and Encore Service Manual. A 24mm 6-point socket (3/8" drive, sold as an oil filter wrench) that I bought actually fits my filter cap perfectly.Don't believe everything your service manager tells you.
Your service manager is wrong as usual and tries to make it sound more complicated than it really is. The head nut on the filter cap is 25mm and it says so right on it. The torque spec is 10 ft-lbs or 14 N.m. Which is not a lot!!!
There's a lot less price difference here ($7.56 US for yours vs $8.99 for mine). I chose a 3/8" drive socket vs your 1/2" drive socket primarily because my low-range torque wrenches are 3/8"drive.They don't have it on their Canadian site and Amazon.com won't ship this item to Canada and it's more than twice the price.