I got an excellent question from Brokedoc, and has his consent to post the Q and the A:

"I understand how synthetics resist degradation better at high temps and have better additives and fewer contaminants, but why do they improve MPG? If you have a 10W30 syn and compare it to a 10W30 dino, aren't they both the same viscosity? Otherwise, what use are the ratings?"



Brokedoc - normally I do not answer one-offs for obvious reasons - not because I do not want to help, but because I get asked, and answer, multiple times.

1) First, the difference between syn and min in this area has narrowed greatly. 10 years ago, the difference was huge, because hydrocraking of mineral oil had not been perfected (Pennzoil built a $300M plant to do it first). Wax crystals in the mineral oil get friendly when it gets cold, and thicken the oil, causing it to reduce power due to pumping losses (called parasitic loss). Today's better minoils (like Havoline and especially Motorcraft 10w30 and 5w20 synblend) use Group III hydrocracked base stocks, which have vastly purer, and far less waxy structures. So with that and what are called pour point depressants, the MPG gap from thickening is lower, although the best synoils have a slight edge. If you live in Antartica, I guess it could add up).

2) Second, and where there is a greater advantage, is that mineral oils, even hydrocracked ones, still consist of poly-molecular structures - oil molecules of different sizes. So like having marbles and a bowling ball in a pipe, this combo causes self-friction and resistance. Not only does this increase drag, but it actually causes minoils to heat themselves up to some degree by thgeir own self-inertia!

The viscosity advantage is really a "trick" the oil companies do. Mobil 1 tends to formulate its viscosity at the lower end of the 10w30 scale. Lubrication Engineers and Red Line at the higher end. So M1 has less vis, and therefore less parasitic drag. It is small, but adds up. I do not consider this deceptive, since M1 is a fine lubricant, and even a thinner M1 can provide severe service protection that eclipses Honda's house brand oil, which has a higher nominal viscosity. Get it?

Again I stress - today's better minoils have greatly closed the gap between the syns and mins of just 10 years ago. Advances in anti-wear and anti-friction additives (which are about the same across min and syn product lines) have made the mpg "gap" far more an issue of driver technique than oil, in most normal day to day driving.

Although I was at the cusp of the synoil movement in the early 1970's and wrote numerous articles on their advantages, I have retained an open mind, and have continued to study the tribologic properties of min and syn available today.

I recommend that if you change oil a lot, lease a car, do not run the car hard in hot climates, do not tow anything, do not track the car, then a mineral oil like Pennzoil or Motocraft or Havoline makes great sense.

If you plan to keep your car forever, run it hard, live in an extremely hot or cold climate, like the idea of using the best oil out there, etc. then a top synoil or synoil blend is a choice worth considering. But changing it before 7500 miles or 6 months is a sheer waste of money and resources.

I like Lubrication Engineers 8130 for a variety of reasons. I also highly recommend Motocraft's 5w20 synblend for those that want to use factory recommended viscosity.

Another recommendation is to can a quart of an ester-based synoil, like Red Line and some of the Motul line, to your minoil. You will get the start-up and lkong time between start advantages of an ester, and it will boost the oil's service life far more than 1 quart in 5 would suggest (20%). It is just an interesting quirk of oil lubrication.

You really cannot go wrong with any of the brand name oils out there. The manufacturers demanded better oil from the oil companies, and that led to huge advancements in the 1990's. And the new API standards coming will up the performance even more in the coming years.

 

Very informative and well-written. Thank you.

 

some good technical info...

and for non-techies, these are some reasons why IMHO synthetics rule

http://www.searchforparts.com/import...gine_life.html

http://www.texassynthetics.com/whyis.htm

http://www.synthetic-engine-oils.com...vs-mineral.htm

be sure it's synthetic
http://www.pecuniary.com/newsletters...csdefined.html

http://www.paonline.com/amsdill/syntheticoil/

good info with reference links
http://www.nordicgroup.us/oil.htm

 

cvajs: Some good stuff, but look at some of the sources - Amsoil dealers?? The are still talking like it is 1985!! My points about the advances in minoil technology from hydroisomerization and/or hydrocracking would de-fuse and make most of those posts anachronisms. The point is, additive technology has benefited both min and synoils, while the advances in minoil have greatly narrowed the gap. GIII "synoils" are now allowed to be called synoils, so what is the difference between US Syntec and Motorcraft 10w30, other than the price.

Also, I have seen many independent wear analysis tests where minoils actually outperformed some minoils. How can that be? Well, a tribologist who has kept up with recent research findings would know that some additives actually "take" better and become effective at lower temps in Group II mid-continent paraffinics than synoils - yes, in synoil it can take a min temp of about 200 degF for them to start working. It takes a while for the oil to reach that temp, so if one is driving Saturday morning errands, the oil may not reach those temps, and the anti-wear additives are less effective. This is one reason that very "engineering" and not "marketing" oil companies like Lubrication Engineers actually blend Group IV synoils with GII basestocks, and while the "oil snobs" and internet marketers like Amsoilites thumb their nose at them, in the tests I have seen by independent, non-aligned technologists, LE synblends show some of the lowest wear and most resistance to TFOUT (total oxygen uptake, a measure of oxidation proclivity) of ALL oils.

Food for thought. Again, min for short hops, syn for long hauls is a good rule of thumb. Times change - technology moves on - those who use the minoil technology (I do not say petroleum, as most syns are made from petroleum too) of 20 years ago to "prove" their products greatness shoot themselves in the foot, when exposed by someone who has no vested interest.

 

RR,

Excellent and through write up as always! I would like you to clarify your statement in regards to adding an ester based oil to your min oil suggestion. Are you saying that you should add it ON TOP of the full fill capacity (4.5qt min + 1qt syn) or are you saying you should add it to reach the recommended capacity(3.5 qt min + 1 qt syn)? My brain is a little slow today .

Thanks,
dsc888

 

Hey Road Rage this is a little off your topic but what exactly was the ARCO Graphite motor oil sold back in the late 70's. They made great claims for the oil and it was the blackest oil I ever saw.