There are available many semi- and fully-synthetic oils which are formulated for diesel engines.
Who told you it was not good? You can and should use full synthetic in a 150cc air cooled engine.
Always use synthetic oils in BMW's.
Depending on what you are looking to accomplish, there are many different oils you can use. Valvoline 5W40 synthetic, mobile 1 synthetic, 5w40 Castrol synthetic are all good choices.
The Owner's Manual specifies 10W-30. I use Quaker State Full Synthetic but traditionally, one uses non-synthetic engine oil for a 4-cylinder engine. As long as you use 10W-30, you really can't go wrong. Try not to mix synthetic and non-synthetic oils. Check what was used in the last oil change and use as close to that as you can.
No they shouldn't be mixed as they have different viscosity Actually, yes you can......but you are wasting your money. Mixing the two reduces, significantly, the positive effects of the synthetic oil. Only do it if you have to, but they are compatible. There are oils available that are a synthetic blend of standard oil and synthetic oil.
Oils
Yes you can use a synthetic blend or 100% synthetic.
No, old oil can use synthetic engines
For a 2003 Jaguar X-Type, it is generally recommended to use fully synthetic 5W-30 engine oil to ensure optimal performance and protection, especially in varying temperature conditions. Fully synthetic oils provide better lubrication, improved fuel efficiency, and enhanced engine cleanliness compared to semi-synthetic oils. However, always check the owner’s manual for specific recommendations, as engine condition and driving habits may also influence the best choice.
The service computer is pre-set for 10,000 mile oil change intervals(A service, B service). You can only get this milage using a synthetic engine oil. Also keep in mind new from the factory the engine has been serviced with a pure synthetic oil which is NOT compatible with a mineral based oil. Also all the engine seals are of a polymer rubber designed to withstand the chemical compound used in synthetic oils. I understand you are asking due to price of the oil, however considering you get 10,000 miles between changes, the engine is started with a lubricationg film still in place ( cylinder walls, bearing, etc..) which reduces the damaging impact cause during engine start, the synthetic oil is the way to go!! Use Mobil 1, you will be glad you did. My Benz, BMW and Porsche all use Mobil 1 as requested by the producer of the car. Edit: I'm not going to overwrite the nonsense above, I'll just correct SOME of it. For one thing, synthetics are compatible with conventional oils. Feel free to verify this on mobil1.com or valvoline.com: Mobil 1: "Mobil 1 is fully compatible with conventional motor oils, semi-synthetic motor oils and other synthetic motor oils, should it be necessary to mix them." Valvoline: "Switching between synthetic and conventional oil does not cause problems. Because the oils are compatible, you can switch back and forth as often as you like." Also note that some oils are "synthetic blend", which literally means a single product that is a mixture of conventional AND synthetic oil types. Not compatible? Yeah, uh... OK.
You can use essential oils or fragrance oils specifically designed for soap making to add scent to your soap. Essential oils are derived from plants and offer natural scents, while fragrance oils are synthetic and offer a wider range of scents. It's important to follow guidelines for safe usage and recommended concentrations when adding fragrance to your soap.