Semi-synthetic yata.
Yes you can change between synth and semi. No problems. I've done it before and no adverse effects.
Quote from
http://www.carbibles.com/engineoil_bible.html
"There is no scientific data to support the idea that mixing mineral and synthetic oils will damage your engine. When switching from a mineral oil to a synthetic, or vice versa, you will potentially leave a small amount of residual oil in the engine. That's perfectly okay because synthetic oil and mineral-based motor oil are, for the most part, compatible with each other. (The exception is pure synetics. Polyglycols don't mix with normal mineral oils.)
There is also no problem with switching back and forth between synthetic and mineral based oils. In fact, people who are "in the know" and who operate engines in areas where temperature fluctuations can be especially extreme, switch from mineral oil to synthetic oil for the colder months. They then switch back to mineral oil during the warmer months."
Where in throttle body is the adjustment the bizscew or on fix SAS
high idle RPM at engine start