Synthetic Oil vs Regular Oil

What Is Synthetic Motor Oil?

Synthetic Motor Oil- Mobil 1
Image Source: Dr. Penny Pincher

Conventional motor oil (also called regular motor oil) is refined from crude oil pumped out of the ground.  Crude oil contains hydrocarbon chains ranging from very short (thin liquid) to very long (thick liquid or gel).  During the refining process, the crude oil is separated into different thicknesses to create products for specific purposes.  Even though the refining process creates petroleum products of similar consistency, there is still a lot of variability in the hydrocarbon chains that are contained in regular motor oil.




Synthetic motor oil is made in an industrial process.  The specific length of the carbon chains can be controlled by the manufacturing process to create a more consistent motor oil.  The result is that synthetic motor oil can withstand higher temperatures and is more slippery than regular motor oil.  It takes a lot of energy and processing to make synthetic motor oil in a factory- this is why it costs more than conventional motor oil.

Advantages of Synthetic Motor Oil over Regular Oil

Regular Motor Oil / Conventional Motor Oil- Pennzoil
Image Source: Dr. Penny Pincher

Synthetic motor oil is carefully formulated to function well for lubrication and heat transfer in the harsh environment on an automobile engine.  Regular motor oil breaks down more quickly under the high temperature in an engine.  Synthetic motor oil lasts longer- it continues to deliver effective lubrication and heat transfer to an engine longer than conventional oil.




The longer life of synthetic oil means that you could go longer between oil changes, potentially making up for the higher cost of the oil.  This also has the advantage of contributing less waste to landfills and recycling centers.  If you can go twice as long on an oil change, you are throwing away half as much used motor oil and half as many used oil filters.

Another advantage of synthetic motor oil is improved gas mileage.  Synthetic oil is really slippery stuff and retains excellent lubrication properties for a long time compared with regular oil.  Better lubrication means that you waste less energy on friction and get more efficiency from your engine using synthetic oil.

Disadvantage of Synthetic Oil

Sometimes Conventional Oil is Better...

In the early days, synthetic oil caused problems in many engines.  The additives that condition seals inside the engine were not the same as in regular oil.  Seals dried out when running on synthetic oil, and even newer engines would start leaking oil.  This problem has been overcome by advancement in the formulation of additives to synthetic oil.

However, oil leakage is still a problem with older engines.  Synthetic oil is so slippery that it leaks more easily in older engines than regular oil.  My Honda Civic with about 170,000 miles had been running great on full synthetic oil- then it started leaking oil.  After some research, I decided to switch from full synthetic to regular oil.  The oil leaking completely stopped after changing from synthetic oil to regular oil.

Cost of Synthetic Oil vs Regular Oil

Synthetic oil costs about $8 per quart for name brands like Mobile 1.  Regular motor oil costs about $5 per quart for name brands such as Pennzoil, Valvoline, and Quaker State.  So, a rough estimate is that full synthetic oil is about twice as expensive as conventional oil.

What about Cheaper Synthetic Blend Oil?

Synthetic Blend Motor Oil- Motorcraft
Image Source: Dr. Penny Pincher

Synthetic Blend is a mixture of synthetic oil and regular oil.  The main advantage of synthetic blend is that it costs less than full synthetic oil.  The cost of synthetic blend is about $6 per quart.  The performance of synthetic blend oil is intermediate between full synthetic oil and conventional oil.  You get some of the benefit of synthetic oil and pay some of the extra cost.

Is It Worth Spending More on Synthetic Motor Oil?

Synthetic Oil Recommended For Newer Cars and Highway Driving

My opinion is that if you drive a newer vehicle and drive mostly highway miles, using full synthetic oil is a good value.  You get better protection for your engine, you get slightly better gas mileage, and you can go a bit longer between oil changes.  All of these benefits are possible because of the increased performance of synthetic oil relative to regular oil.

The extra cost of synthetic oil can be largely offset by going slightly longer between oil changes than you would if you were running with conventional oil.  For example, the oil change interval for my Honda Civic is 10,000 miles.  If I am running conventional oil, I might go in for an oil change every 5,000 to 7,500 miles.  With full synthetic, I would be comfortable going the full recommended oil change interval between oil changes, reducing the number of oil changes I would need.

Synthetic Oil Not Recommended For Older Cars or Severe Driving Conditions

If you do stop-and-go city driving, or short trips that do not fully warm up your engine, you might want to consider more frequent oil changes.  Your oil will need frequent changes due to increased contaminants from your engine accumulating in your oil and  from faster break-down of your oil under severe driving conditions.  The need for frequent oil changes makes synthetic oil less attractive.  Conventional oil might be a better option if you are doing frequent oil changes anyway.

The life of the oil filter is another important factor.  Oil filters consist of paper filters and have a pretty limited life.  Even if your oil can go a long time, your filter is a limiting factor on how long you should go between oil changes.  Severe driving conditions can shorten the life of your oil filter as well as your oil.

If you have an older engine, synthetic oil may tend to leak more.  If your car is leaking oil you may want to avoid synthetic oil.

Can You Save Money Using Conventional Motor Oil?

Conventional oil is less expensive than synthetic oil.  If you change your oil frequently, you can save money by simply using conventional oil since it is less expensive.  You can save $20 to $30 per oil change using conventional oil rather than synthetic oil.  The value of synthetic oil is that it can last longer and offer better protection for your engine.  Conventional oil is adequate for normal driving conditions if you change the oil frequently enough.  Using a synthetic blend is an option to get some of the benefits of increased protection and oil life without paying the cost for full synthetic oil.

Penny Pincher Journal

Copyright © 2013 Dr. Penny Pincher.  All Rights Reserved.  Privacy Policy