Depends.If you're having the engine flushed or rebuilt you can go to synthetics afterwards. But if you've been running the engine on "natural" oils before you might want to be a bit careful. Synthetics have been rumored to dissolve old deposits in the engine, which can then drift around and cause damage.
Depends on which classic car.
It would not be as good as all synthetic however mixing the two should not do any damage to your engine.
5w-20 of any synthetic motor oil brand.
I dodged the bullet on that one by not using synthetic oil in my car. If I did, I would be sure to change it at least as often as my owner's manual stipulates so I don't void my warranty.
Some cars as well as aircrafts use synthetic oil. Whether you should use it in your car or not will depend on the age of the car as well as its milage. If its too old, its probably not a good idea.
chip oil or fat
its the same process as changing synthetic oil, except you use regular oil.
5w30 synthetic
form_title= Synthetic Oil form_header= Put synthetic oil in your car with help from the pros. When was the last time your oil was changed?*= _ [50] Have you ever used synthetic oil before?*= () Yes () No What type of oil do your currently use?*= _ [50]
If it is the synthetic blend, you should change the oil every 3,000 miles. If it is a full synthetic, you should change the oil every 5,000 miles.
20-50 synthetic
That's okay.