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The Great Debate: Should Your Truck Be Using Synthetic Lubricants?

They're expensive, but they appear to work...

By Granville L. King

This article appeared in Pickup, Van & 4WD Magazine
December 1979

WITH THE worldwide crunch on mineral oils and with U.S. gas now at $1 a gallon, synthetic lubricants would seem to deserve a second look. Many of us regard them with considerable askance. Yet, prominent and responsible citizens and organizations use them religiously. However, numerically, the users are rather small. Theoretically, synthetics have everything going for them. So why haven't they taken over the scene.

Probably the biggest reason is that the average man distrusts the claims made about them, which, for some manufacturers, rank high in the snake oil category. In addition, the more reputable manufacturers candidly state that their products are not Instant Fixes for All Ills. The fact is, it sometimes takes 2000 miles for a good synthetic to show best results. So, we have the case of (1) something we tend to distrust and (2) a case where we can't instantly measure — between morning and night — the advantages received.

Then what about the truck makers: Why don't they put synthetics in all the new vehicles? The answer is a left-hand compliment: Synthetics are too slick. They won't break in a new engine and seat the rings properly. You must use conventional petroleum products to attain the proper degree of abrasiveness for this task. So they dare not send machines out of Detroit with the too-slick stuff included.

Well then, surely the Army uses synthetics in everything: it does use synthetics in jet aircraft and other high temperature environments. But it doesn't use them in vehicles of the ground type nor for any save very special applications. Why? Because the Armed Forces works on the lowest bidder principle. Synthetics cost approximately four times what conventional mineral oils and greases cost.

A final reason for lack of synthetic acceptance is that very few filling stations carry them. You can't just roll in anyplace and ask for a quart of your favorite; on a long trip it's wise to have some along with you just in case. So it all adds up to a rather negative picture, comparable to convincing folks how much better they'll feel if they just stop smoking.

Oddly enough, synthetics originated for two totally opposed reasons, to (1) combat extreme cold and (2) to combat extreme heat. The first case is illustrated at least partially by the fate of the German Army in Russia during WWII. At the very gates of Stalingrad and Moscow the army's rolling stock — including tanks — simply couldn't move in the terrible cold. Hitler put his scientists to work and they, in fact, came up with additives which fixed the problem. But by that time, they had malcontents like Gen. Patton, et al, knocking on Berlin's gates and it was too late.

In 1946-'47 the British, who hardly ever do things for the same reasons that other men give, came up with ester synthetics for a quite opposite application. They needed to provide lubrication in the high temperatures of the day's --- then new — jet aircraft. They were quite successful in this use. And today's jet engines stay alive only through the use of such lubricants.

So what are synthetics, really? Are they some strange chemical combination completely divorced from mineral oil lubricants? Are they good only for storming Stalingrad or running DC-lOs? Or do they have wide, general applications to our trucks as well?

First, they all derive from some kind of petroleum base, but there's no typical synthetic in the way that mineral oils are typical. Their ingredients are a crazy, mixed-up bunch of things like (1) synthesized hydrocarbons, (2) silicones, (3) polycols, (4) phosphate esters, (5) organic esters, (6) dibasic acids, (7) alkylated aromatics, (8) halogenated hydrocarbons and much, much more. The important thing is that they're not simply cracked down from crude oil but are specially invented for each specific purpose. And, for today's practical view, they break simply into two classes, esters and hydrocarbons.

Esters come from an interaction between alcohol and acid; hydrocarbons are created atom-by-atom. Relating to real life, they look basically like this:

1. Diesters or dibasic acid esters such as AMS/OIL or Eon E-Il.
2. Polyesters such as "All Proof" and Eon D-20.
3. Polyalphaofins (hydrocarbons) as used for the base of Mobil 1 and Chevron "Sub-Zero."
4. Alkylated benzenes (hydrocarbon) used in Conoco's Polar Start DN-600.

A brief re-read of the various ingredients gives you a clue on the acceptance problem: Who, in Heaven's name, wants "acids" or "carbons" or "alcohol" rushing about to lubricate his machine? Far easier to say, "just put in a quarta 30 weight, Charlie." And, unlike synthetics, it's nice to know that Charlie always has it.

Thousands of different lab tests have been made on synthetic oils. Some of these tests prove something worthwhile; others only provide more grist for the Madison Avenue mills. For instance, to start an engine is always a big deal in synthetic ads. And lab tests have shown that with the same well-tuned engine, under the same condition of minus 40 degrees F., the conventional oil will require approximately 280 ampere-seconds while the synthetic will require just 22 ampere-seconds. (The ads, naively, fail to include the rate, that is, "- seconds," which makes the expression "280 amps" or "22 amps" meaningless as a function of power usage. But, "Ampere-seconds" is what they mean.)

So that sounds pretty great! You get a near 13:1 improvement with synthetics, etc., etc. But does it, taken in that context, mean anything at all? Of course it doesn't. With the conventional oil the engine took 140 amp-seconds. With the synthetic the engine took 110 amps/second for 0.2 second for a total of 22 amp-seconds. The battery power lost by use of the conventional oil is replaced almost instantly by the alternator. A stock 45-amp alternator need run only some 10 seconds to replace all the power "taken out," plus a bit more.

What such a test does say is that internal engine friction is dramatically reduced. And if your engine is just barely starting — unable to turn fast enough for reliable ignition — the synthetic can make a profound change. What it shows is that synthetics act like a very thin oil at low temperatures; you could, in fact, get the same good cranking results with 5W or by adding a few quarts of kerosene. But such a lube change would kill your engine's bearings once the engine became heat soaked.

Viscosity is all-important in lubrication, naturally. Yet, retention of viscosity is something we hardly ever think about. We know our oil goes thinner when it's hot and that it thickens up again when it cools. But hardly any oil returns precisely to its original viscosity once it's been made very hot and then cooled. For instance, the industry classic "Oldsmobile IIIc High Temperature Test" shows that regular oils increase their viscosities by frightening factors of between six and 10:1 during the standard 68-hour continuous run. That means your good-penetrating 20W can quickly turn into something a differential would be more at home with! It's not uncommon for garages to pull out the wrecked engines of big-bore V-8s and find you can bounce the crankcase oil around like an oblong, semi-cured rubber ball! Esters, however, under the same conditions, show a maximum of 7.5-percent viscosity increase, and hydrocarbons run at approximately 34 percent in their increase. These numbers, 7.5 and 34, are a long way from the 600 and 1000 percents of the conventional oils.

Look also at temperature-use range. Regular oils pour down to about zero degrees F, some slightly below that. But synthetics not only pour down to zero, but to minus 60, where conventionals are totally solid. If the Nazis had this in 1942, our primary language might not be English.

The other end of things shows another disproportionate difference. Regular oils essentially stop lubricating at 300 degrees F and most display flash points at around 350 degrees F. Synthetics are nearly all good into the 400-470 region, displaying no oxidation. The special Gulf Synfluid, doesn't flash until upwards of 710 F.

Do we really need this kind of extended range? Well, with lower compression engines, maybe not so much. But it is a fact that our conventional oils/lubricants have just barely been adequate for many, many decades. Pull the valve cover from any engine that's used conventional oil products for the past 50,000 miles. The inside will be covered with tarnish and black oxidation. Now pull the cover from a similar engine that, since break-in, has been run only with synthetics. It'll look like a mirror — or as much a mirror as it was when new. Carry that thinking on inside the engine to its multitudes of hot spots and the picture looks very good for synthetics.

The proof of the pudding, however, is shear strength-in other words, the amount of lubricity protection you get. Southwest Labs of Texas, as well as others, show that film or shear strength in conventional oils runs 400-700 psi. This test is made by putting a lubricant between two pieces of metal and seeing what it takes to squeeze it out. How did synthetics come out in this test? They ran in the 3200 psi region, four-to-eight times better than conventional oils. The question arises, do we, in fact, need this astronomical improvement in shear strength for conventional use of vehicles which operate in a comparatively narrow environmental band?

In answer I would say there is a bit of overkill here; we don't "need" all this increased capability. It won't make our engines and moving parts last from four-to-eight times longer. But it takes us well out of that region of lubricants that have been just adequate and gives our machines a potential that, to me, more properly relates to their present $10,000 cost.

We might also mention that synthetics, being less volatile than conventional oils, evaporate approximately 45 percent less. This is one reason why over-the-road truckers sometimes get by with 100,000-mile synthetic oil changes; it simply hangs around longer, assuming no leaks or dribbles.

Extensive field tests of at least one synthetic vs. conventional lubes were planned and we were all set to go ahead on them. But as we learned more about synthetics and their characteristics, it seemed evident that such a test would be (1) excessively localized, (2) short term and, probably, (3) inconclusive. True, I used a synthetic in all my vehicles —- a van, a two-stroke off-road bike, an aged Jeep and an outboard motor. It (AMS/OIL) worked great so far as I know from about 2000 miles of use on each engine. Engine loudness was greatly reduced on the outboard and bike (via db meter tests), all engines ran smoother and could have their idle dropped to where you could count the crankshaft revolutions. Mileage in the van/Jeep went up five to eight percent.

But more important than this personalized experience are the findings from men and institutions that have run trucks professionally for many miles and many years with synthetics. So I got a raft of user letters from AMS/OIL; that, incidentally, is all I got from AMS/OIL. I laid down $50 of my own hard-earned cash for a case of the stuff.

Carrying enlightened skepticism a step further, I got on the phone to a random sampling of those who had written the letters. My questions were simple: Did the man, in fact, write the letter, was his experience as the letter reported, and was he still using the synthetic?

All answers but one were frighteningly enthusiastic! And that one was a fellow who'd just joined the company and couldn't dig up cost-comparison records. All in all, AMS/OIL came off with very high marks!

Smokey Yunick ran some interesting tests on a 302-cid Chevy engine wherein he compared the difference between a good racing oil and the All Proof synthetic. He got an 8.1 hp increase at 1800 rpm and a 24 hp increase at 4000 rpm. This tailed off to a 20 hp increase at 5600 rpm. These numbers are rather modest compared with the claims made by some synthetic marketing groups. But, in a Smokey-prepped engine, they're significant.

What we're dealing with here is a material which can act like water-thin oil at extreme low temperatures, one which displays fantastic shear strengths at extremely high temperatures, one which essentially does not modify its basic viscosity, and one which has negligible evaporation. It seems like the right kind of stuff to put into a pickup, van or 4wd!

The cost trade-off runs into a bit of mathematics; synthetics cost approximately four times what conventional oils cost. But, the argument goes, they last four times as long — change oil at 25,000 miles instead of the more conventional 6000 miles — so cost appears to be a standoff. However, most synthetics warrant their material for 25,000 miles or one year, whichever comes first. So if you run 12,500 miles in a year and then change your oil, you've doubled the long term cost of synthetics, making it, in that context, twice as costly as conventional oils over the years.

Popular Science, a rather workmanlike magazine, verified a 100,000-mile run with synthetics. And most of the truckers I talked with who run synthetics, get the same, or nearly the same, mileage between changes. However, in our back country stop-and-go driving, and our bumper-to-bumper on the salt mine freeways, it might not work out that well. Truckers run in as near a steady-state mode as they can keep it; we often use our equipment in the least advantageous manner. The payoff seems to be that if you put a lot of miles in during a short period of time — like 50,000 miles per year — you might be able to think along the lines of extended oil change periods.

However, even if you didn't save oil-cost money directly from going to synthetics, its other advantages seem to make them rather worthwhile. Mileage definitely will increase, though perhaps as little as $40 per year, the worst case quoted in the AMS/OIL letters. However, even at $40 per annum, you're ahead of the game. And you still have the cold weather starting capability, the high shear strength, the longer life for all drivetrain elements and the other good features.

Take one final thought along with you; the feds, in their regulations for greater mileages in future vehicles, give synthetics another one of those left-hand shots. They baldly state, "No manufacturer is permitted to satisfy his allocated mileage increases via the use of synthetic oils/ lubricants." That sounds to me like somebody's trying to tell somebody something! Balefully, they're saying not to play with loaded dice.

But, when the dice seem loaded in our favor. . . .

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