I was working for a Dodge dealer when Chrysler began running synthetic & for quite some time were told by experts & engineers not to switch to synthetic on older or any high mileage vehicle. Not to ever mix synthetic with conventional or different weights. Man I've worked parts & services for Mercedes, Cadillac, Chrysler, GM.. They told us that for liability purposes only. Personally, unless it was on commercial equipment, I wouldn't run it. For personal use conventional oil rarely gets a chance to break down. You need to change it every every season regardless. Unless you're mowing over 3 thousand miles every 3 months. Lol
Some people said it already. As long as it has motor oil. If synthetic puts your mind at ease, I ain't mad at cha. Lol
I follow the manufacturer on viscosity & that's it. Manufacturers will tell you to run an oil type & brand because they're trying not to get stuck with a huge order someone got a kickback on. Once it gone, it's back to recommending jusr brand.