I have a coupon for a free oil change with a synthetic blend. I have been told by a few people that if I go to a synthetic blend, I will never be able to go back to regular oil. Is this true? Will it do any damage to my car if I use the blend once and go back? I don’t want the extra cost forever, I just wanted to use my coupon.
You can go back and forth anytime you want. Oil is oil. Going to synthetic or syn blend does not change your engine in any way.
No, it’s not true. You can switch back and forth between synthetic and regular motor oil any time you want. Your car’s engine doesn’t care.
No problem with switching, but what’s with the ‘free oil change’ coupon - makes me wonder about what they’ll be trying to force on you - power steering flushes, that kind of thing. Watch you wallet!
Agree; use the coupon, but resist other “offers” or scare tactics that your car is falling apart. Again, your car does not care what the type of oil is, as long as it is the right weight (viscosity). I once took my car for a free front end alignment at Sears and was told that my whole front end was “shot”. These guys are all on commission.
Your “few people” have a very rich imagination! They probably heard the story that you should not put synthetic oil, which is very slippery, in an old worn engine, since it may start using oil. That part is true.
Great! Thanks so much for clearing that up. I won’t feel so bad using my coupon! 
you can use any,synthetic is supposed to offer better protection,and last longer than mineral oil,just use the correct viscocity,and you will be fine!just be careful with these free coupons,because quite often a garage will entice you in with something,then say “you need a new shock absorber”,or something else,just to get some money out of you!(well thats the case over here in the uk )
One of those stupid myths like Bigfoot that’s been circulating for years. Probably started by one of the oil companies that wasn’t making a synthetic oil at the time (pretty much every one does now). You can go back and forth…mix and match…your engine won’t know the difference. Bigfoot may know…but your car’s engine won’t.
As long as we’re on the subject… if you fill up with synthetic, can you safely extend your oil change interval? I’ve heard conflicting stories, such as the additives get used up just as quickly as dino oil.
When synthetics first came on the market, they had some ingredient/property that would cause an engine’s seals to swell a little. That alone didn’t cause any problems. However, if you then switched back to dyno oils, those seals would shrink and the engine would experience oil seepage or leaks.
That issue hasn’t been a concern for years. As others have said, you can now go back and forth anytime you want.
As “texases” said, be careful with the “free oil change” coupon. They can be very expensive.
It’s NOT the additives that make synthetic oil last longer…it’s the oil itself…and LACK of additives. Synthetic oil is basically a more PURE oil. Dyno oil has a lot of contaminates…synthetic oil is built from the atoms (almost) up.
Yes you can extend the oil change interval by using synthetic oil. By how much…not really sure. What happens to ALL engines no matter what oil is used is the oil gets contaminated from use. Most of those contaminates can NOT be filtered out. The only way to get rid of them is to drain the oil and refill with fresh oil. Synthetic oil is a far better oil…especially if you run extreme hot and cold…But it’ll still get contaminated.