Mixing two kinds of oil will in most cases not cause any problems, but if i where you, id take out the old oil and put in the new.
no
Have it changed to the proper oil.
It can be. The 5w20 is the weight of the oil which you can buy conventional or synthetic. If it is synthetic it will say so right on the container. If it does not say synthetic it is conventional oil.
Yes, you can even mix synthetic with conventional oil.
It is a combination of synthetic oil and conventional oil.
It is conventional oil and contains no synthetic oil. 3000 & 5000 are part synthetic and part conventional. 7000 is a full synthetic oil.
You cannot tell by looking at the oil. Owners manual will tell you. You can use synthetic even if it came with conventional. But if the manufacture recommends synthetic then by all means use it.
I will change my oil from conventional oil to synthetic oil on my next oil change.
Semi synthetic or synthetic blend is a combination of synthetic and conventional oil. Full synthetic oil is just that 100% synthetic oil.
You can use conventional or synthetic oil in your Toyota. Unless you do some towing, driving in the mountains, or drive in hot temperatures synthetic oil is of no real benefit.
You can use synthetic, synthetic blend, or conventional oil. It is your choice.
Synthetic and conventional oil can be mixed and used with no problem. That is exactly what a synthetic blend that you can buy is. A mix of synthetic oil and conventional.