Want this question answered?
Use SAE 10w-30 Synthetic oil such as Mobil 1.
Mobil 1 Racing 4T SAE 10w-40 Synthetic.
SAE 10 weight oil
Manufacturers mix various oils to make an 'SAE 40' oil product. Such a mixture will not have a molecular weight.
Any SAE 5W-30 brand oil, unless you are located in an extreme cold climate, then a SAE 0W-30. I prefer to use a fully synthetic oil (Mobil 1) due to its proven durability and reliability, but any brand will due as long as you follow the recommended intervals for changing the oil/filter.
SAE 30 oil.
SAE 10w30
SAE 50 is a single weight oil that is 50 weight when cold or hot. SAE 20w50 is a multi-grade oil. When cold it flows as a 20 weight oil and therefore flows much easier. At full operating temperature it flows as a 50 weight oil. The W stands for winter.
All oils are SAE. If you mean: going from synthetic to conventional (petroleum-based) oil--no problem. They even sell Blends. If you ran synthetic, exclusively, for a while , with no problems, your engine is kept cleaner. So, be sure you replace the oil filter when going back to conventional. That's all.
It they are the same weight oil as in SAE 30 weight oil there is no difference and they are identical. 30 weight oil is 30 weight oil synthetic or conventional.
Thinner weight oil flows more easily that thicker oil. Most new cars today use SAE 0w-20 or SAE 5w-20 weight oil. This weight will protect you in all temperatures. If however you drive an older car that uses SAE 10w-30 or SAE 10w-40 weight oil then you might want to use a slightly lower weight oil in extreme cold.
SAE 10w30.