Can you put conventional oil in your car if have had synthetic it previously?

Yes, you can put conventional oil in your car if you have had synthetic oil in it previously. While synthetic oil is generally considered to be superior to conventional oil in terms of performance and longevity, it is not harmful to switch back to conventional oil if necessary. However, it is important to note that once you have switched to conventional oil, you should continue to use conventional oil for all future oil changes. This is because conventional oil and synthetic oil are not compatible and mixing the two can lead to problems with your engine.