I drive a 2004 KIA Sorento 4x4. I drive about 5mi a day. I used to commute about 45 min to work on the highway so we opted to use synthetic oil in our oil change. We would like to go back to basic 10W/40 but we’ve been told that if we stop using synthetic it will cause damage to our car. Is it safe to switch back?
If anything you should stick with the synthetic now. Driving 5 miles a day is harder on the engine than the 45 min commute. 10W-40 is a pretty heavy oil by today’s standards, is that what your owner’s manual recommends?
Sorry that’s just a number I remember from my teen years 
I have no idea what the weight is but my hubby would
It is safe to switch back. No serious damage should occur. I have switched from conventional to synthetic and back with no car blowing up yet. I also use semi-synthetic oils, which are part of both.
Old wives’ tale from the start
I would check out the 10W40 business. Most Kias take 5W30 or 10W30 and do well.
Unless your owners’ manual requires synthetic (some do) then there’s absolutely no reason whatsoever not to switch back to dino. Since you’re a short trip driver, use the “severe use” maintenance schedule.
Double check the weight against your owner’s manual recommendations…use only what it recommends. If you’d like to know more, visit www.carbibles.com.
It’s safe to switch back, but why would you want to? Synthetic oil should last about twice as long as conventional between changes, so unless your car uses oil, it should mitigate the additional price involved. In cold weather, it flows better and prevents engine wear better too. Personally, I’d never switch back—synthetic is an order of magnitude better in my personal opinion. If you do choose to do this though, and maintain a regular oil change schedule, no harm will occur.
Synthetic oil was first introduced to allow fleet owners to increase the interval between oil changes. This saved them money by reducing staff, since they changed oil about half as often. Natural oil is fine for your car as long as the manufacturer does not recommend or require synthetic. Be sure to change your oil at least twice per year or as often as Kia recommends. Your oil change is time based rather than mileage based if your mileage estimates are correct.