After the break in period it is not an issue.
yes you can synthetic oil can go in any engine
In a Brand new engine it is recommended that you get the rings seated before you start using Synthetic oils. So run your engine for 3,000 miles and then you can switch to a Synthetic.
conventional. I wouldn't put synethic in it unless it has already had it in the engine. Synthetic is mostly used in high performance or new vehicles. Synthetic won't do anything for an older engine
SAE 10W-30 synthetic oil.
yes
5w30 synthetic
Yes, and I highly recommend you use synthetic in an air cooled engine.
Lucas also makes a synthetic engine oil additive.. Yes.
5W20 synthetic.
Yes
Yes, you can. It is even sold as a Synthetic Blend.
For the first 1600 km's or 1000 miles on a new engine just use regular oil. The reason being is that you want MORE friction in the engine to help the parts wear properly for a good "break in", synthetic oil has such good lubrication properties that it can interfere with proper engine break in.