Some questions about synthetic oil

When I purchased my car, I was told by the salesman to use synthetic oil; that it would decrease the number of miles necessary between oil changes. However, whenever I take my car to that dealership, they always note that they have used synthetic oil and that I will be due for another oil change in 3K miles. Did I simply get ripped off by a salesman who knew nothing or wanted to make his numbers look better?

He said that with synthetic I would only have to change oil twice a year based on 12K/year driving habits with a lot of highway driving.
He also said that once I started using synthetic oil that I should never go back to regular oil.

Any thoughts, please?

A what type of car?? B yes you were sold a bill of goods, 12k oil changes are a bad idea. Period end of story !

What does your owner’s manual say? My 2011 Toyota Sienna requires 0W-20 synthetic oil, but the specified oil change interval is 10,000 miles. Twice a year based on 12,000 miles a year (that is once every 6000 miles) doesn’t seem out of line to me.
If your car doesn’t require synthetic oil, you can switch back and forth as often as you like. I tried synthetic oil in the 2006 Chevrolet Uplander that I used to own, but couldn’t see any real advantage, so I went back to ordinary oil. The switch back didn’t cause any problems.

I have a new Sonata and I can look it up in the owner’s manual for you.

The manual says nothing about synthetic oil. That means your car will be quite happy with natural crude oil. The change interval is 7500 miles if you have the 2.4L engine and 5000 miles if you have the 2.0L engine with turbo.

And if you have already used synthetic oil, it is perfectly OK to switch back to natural oil.

Disregard anything else that you may have heard from either the salesman or the service adviser. The owner’s manual has the last word.

Follow the instructions in your owner’s manual. If it allows regular oil, you can switch back.

This dealership appears to be recommending more service than necessary, so you’ll always need to be a little suspicious of anything they tell you. Perhaps there’s another nearby dealership that can be trusted more.

The only reason to take a car to a dealer is if it needs warranty work…If you have a turbocharged model, there might be some advantages to using synthetic oil…But otherwise, stick to what the owners manual recommends…

Maybe I’m wrong, but I read this as an oil change every 6 months/6k miles with mostly highway driving. That’s not too bad of a recommendation if the environmental conditions are not too severe.
In OK with the humidity and dust that interval could be a stretch.

“I was told by the salesman to use synthetic oil; that it would decrease the number of miles necessary between oil changes.”

Hmmm…most people would consider that decreasing the number of miles between oil changes is a negative factor, so I’m not quite sure why this would be a selling point. Most salesmen would try to convince you that the more expensive synthetic oil allows you to increase the number of miles between oil changes.

And, then we have the service department that is undoubtedly trying to get the OP to change her oil more often than is really necessary.

The simple answer to this question is to utilize the maintenance schedule provided by the manufacturer. It is contained either in the Owner’s Manual, or in a separate booklet with an appropriate title. In that maintenance schedule, there is an elapsed time factor as well as a mileage factor (“every 6,000 miles or 6 months, whichever comes first” is an example of many car mfr’s oil change specifications) for most maintenance procedures. Unless the OP becomes aware of the car’s maintenance requirements and adheres to them, there is a very real chance of voiding the car’s warranty.

As to the salesman’s statement that you can’t switch from synthetic oil to conventional oil, that is also incorrect. Some folks were of this belief when synthetic oil was first introduced, but this notion was debunked many years ago.

Over the years, I have found almost all car sales people to be woefully ignorant about the features of the cars that they are selling, and to be absolutely NOT knowledgeable about car maintenance.

The OP really needs to begin reading that Owner’s Manual.

There are many kinds of cars out there and often the needs for car A is not the same for car B. While the salesman may know what the features are on a new car, few of them seem to have read the owner’s manuals. Also your neighbor may drive lots of highway miles and your car may be driven 2 miles to church. once a week

Back in grandpa's age, the engines and oils were not nearly as good as today's.  

So what to do?  

Let the salesman sell cars and let you take charge of scheduling maintenance.  If you look in your owner's manual, it will tell you how to determine when YOU car's oil needs to be changed as well as what other maintenance it should have.  Read the whole chapter.  You personal driving conditions need to be considered. 

I suggest that you avoid any quick oil change place and most dealerships.  The best bet for most people is to find a local <b>independent</b> repair shop.  Ask friends neighbors etc for a recommendation.

I’m assuming that the salesman said you could INCREASE the miles between oil changes if you use synthetic.

Several things here.

. I can count on one hand the number of salesmen I’ve met who could even change their oil. Most haven’t a clue on the mechanics of any car.
. The salesmen is trying to sell you a car. MOST will say anything to get a sale. This includes stretching the truth to out and out lying.
. I’ve yet to see any manufacturer say that you can increase oil change interval if you switch to synthetic.
. There is only ONE answer…it’s in your owners manual.

The salesman is selling the car, and the service dept. rep is selling services. They don’t line up even at the same dealership. Using synthetic oil and changing it every 6 months and/or 6000 as per the OP’s post is fine.

With synthetic oil you can increase the change intervals to some extent, but to maintain your new car warranty you have to change the oil as specified in the owner’s manual regardless of whether you use synthetic, synthetic blend, or standard oil. You can switch oil from synthetic to regular and back to synthetic without issue.

If you have a turbo charger in your motor I would suggest synthetic oil too. Synthetic oil handles heat better than regular oil and turbo chargers run hot and need a good supply of oil to reduce wear of the bearing(s) in the turbo charger.

3 month and 3,000 mile oil changes with a synthetic oil is overkill and generates more profit and visits to the service dept. No need for such frequent oil changes with synthetic oil and the use the OP describes.

Your owner’s manual tells you how long you can go between oil changes. Consider the owner’s manual to be a MAXIMUM and you’ll substantiall increase the probability of your engine leading a long, healthy, trouoblefree life.

It looks like the saleman was recommending an oil change every 6,000 miles, which I’d consider reasonable, but your owner’s manual is the true gospel.

As to mixing synthetic and dino oils, both are chemically exactly the same except that synthetic is more pure and allegedly contains more consistant sized molecules. Unless your owner’s manual requires synthetic oil, you can mix them to your heart’s delight. You can even buy them mixed, called “blended” on the bottle.

The advice to use synthetic oil combined with the advice to change the oil every 3,000 miles equals lots of extra money for the dealership.

You can go back to normal oil any time you want and nothing bad will happen to your car, and you can probably go longer between oil changes too, depending on what your owner’s manual says about it. Read your owner’s manual and follow its guidelines.

I am really glad that I asked you guys about this. I will definitely read my owners manual.
My car is not turbo charged… it is just a regular Hyundai Sonata, sold to me by a salesman who allegedly drove the same car I bought, and just saw a big fat dollar sign when I sat across from him.

I will have to consider all of the issues I am having with this car and this dealership a “live and learn” experience.


I follow the exact same schedule with my cars, which splitting the driving I do between the two of them, don’t average more than 10-12K a year. One oil change in the spring and one just before winter with full-synthetic. I’ve found that the one car uses very little oil between changes (½ qt.) and the other uses no oil between changes when running synthetic. The old car has over 260K on it and the newer one about 70K.

The salesman gave valid advice with one exception. You can switch back and forth with synthetic to regular oil.

Personally I would stick to the less expensive conventional oil if that is what is required.

The other question is how long are you going to keep it?? If you are not the type to run the wheels off the car then it does not matter AT ALL… If you are going to trade it in with 50K, save your money…

You can switch back and forth with synthetic to regular oil. Assuming the owner’s manual specifies synthetic oil. :slight_smile:

Joseph, the owner’s manual says nothing about synthetic oil. So switching back and forth is perfectly all right.