I've used Sea Foam before on older cars and had good results. Found this article about using it on GDI motors if anyone has any concerns: SEA FOAM CASE STUDIES – GDI REVIVALWe had a 2013 Soul Base 1.6 Automatic (bought new). After 6-1/2 years and 95K trouble-free miles, we traded it last year for a 2020 Soul LX (base) with IVT. The new Soul is quieter, more solid-feeling, smoother riding, and has more comfortable seats. The 2.0 provides more than enough power for us, even here in the mountains of West Virginia. The IVT has been flawless so far, and I personally think it's very smooth and seems to always be in the right "gear". Because of COVID-19, and since we have 2 cars, we only have about 5,500 miles on it, but we have averaged 32 MPG in mixed city/highway. On one trip to Wisconsin, we averaged 42MPG on one tank on 2-lane backroads at 60 MPH.
We bought this model because it did not have all of the safety nannies like lane assist, blind-spot warning, and auto braking. I know how to use my mirrors, and I don't need a computer steering or stopping my car. I also don't want to listen to the endless cacophony of "dings and bells" going off as I drive. All models except the base have most of these nannies standard. We also have a 2019 Subaru Forester (and it has some of the nannies), and I much prefer driving the Soul.
The 2.0 reverted back to multi-port fuel injection (MPFI). Even though our '13 still ran like new at 95K miles, there were concerns about carbon build up with GDI (gasoline direct injection). No worries now. The 1.6 Turbo still uses GDI as well as the Dual-Clutch transmission, which has mixed reviews for smoothness and reliability. Either way, you still get the 10/100K powertrain warranty.