Mobil 1 and other Synthetic Oils

I use synthetic in winter here in Eastern Ontario, simply because it stays more fluid in extreme cold and therefore the car starts better. Otherwise I think it's just a waste of money.

Not a waste of money if you leave it in a bit longer than conventional oil. Many users feel this is OK and it saves user time and conserves resources and money.

Richard.

I thought the rule was that you can't switch back and forth. That synthetic and standard oils were incompatible so once you started with synthetics you have to stay with them. I've always been a little suspicious that this was an idea dreamed up by Mobil's marketing department rather than their chemists but I've never heard it challanged.

The point is that you are supposed to drain the sump completely, in particular when switching to synthetic, otherwise you'll have the old oil degrading before the synthetic, negating the benefits of the synthetic.

DAS

"General Schvantzkoph" wrote

Well I've done that on many cars over the past couple of decades without any problem.

"Richard" wrote

To me the issue is dirt, not oil life. When the oil gets dirty I change it, since my driving is generally light-duty (few short trips, mostly open road, paved roads) I change at 10000 km (6000 miles). Synthetic gets dirty just as fast as regular oil.

Cheers.

Mobil has never claimed that. They are compatible.

Matt

You just have what is now sold as a blend! :-)

Matt

On "poorly maintained" engines and those running what I consider to be too light oil for the conditions, premature timing chain wear, chain tensioner problems, accelerated cam lobe wear, oil pump wear, sticky rings, valve guide and valve train wear were fairly common. Also perforated oil pans (rusted from the inside out) were more common on the neglected engines, but not unheard of even on well maintained engines. On Mitsu 2.6 engines properly maintained those 6 foot long timing chains could last the life of the car, and the balance shafts gave no trouble. Neglect the oil changes a few times, or extend the interval to the maximum "recommended" in the book, and the chains would get noisy early in their life (under 100,000Km), and the balance shafts would seize, snapping the little chain or stripping the teeth off the sprockets. When the timing chain tensioners either wore badly enough or stuck in, they would break and jam the timing chain, or allow the chain to jump a tooth and all 7734 would brak loose.

When the neglected engines were opened up, it was not uncommon to find badly etched bearings as well.

On well maintained engines, about the only thing they got opened up for was gaskets. On some models head gaskets let go leaking either coolant or oil to the outside world. On others the head gaskets blew, letting compression out or coolant into the combustion chambers.

Main oil seals still let go occaisionally, along with water pumps etc

- and of course on belt driven camshaft engines belts had to be changed, and so on. Regardless what oil you use, you eventually, if not sooner, end up replacing the "oil pisser switch".

Let that get bad enough, and total engine failure could creep up on you very quickly - When the "convenience light" comes on, you are about to be greatly inconvenienced.

SOME early synthetics were totally incompatible with standard oils. None that I am aware of today are - and to get an API rating they MUST be compatible.

Actually there are synergisitc benefits of a blend. However, I would not use a commercial blend because they don't tell you the mix percentage, and knowing most companies, they will price it as if it were a 70/30 (synth/non-synth) blend when what you would really get is 40/60 or worse - good for their profits at the expense of naíve people.

If I was going to use synthetic, I would make my own blend by putting in

Bill Putney (to reply by e-mail, replace the last letter of the alphabet in my address with "x")

Exactly! :-)

DAS

How do you know that these failures were oil related? Unless you had all of these vehicles in a very controlled study, it could be that the folks that didn't maintain their vehicles also are the same folks that abuse them in every other way such as prolonged idling, prolonged high speed operation, reving to redline for every shift, etc.

Matt

Name one. I've used synthetics since the mid 70s and, I believe, Amsoil was the first commercially available synthetic and it has been compatible since the start as has Mobil 1/Delvac 1 which is what I've used since probably 1977 or so.

Matt

Matt. I know you will argue, but I also knew the majority of my customers - and MANY of the vehicles I serviced, that had no failures, were abused severely as far as both prolonged idling and high speed operation is concerned. Some were local delivery vehicles (couriers) , some were weekend rallye cars and solo1 and solo2 cars. Some were the same cars coming in for complaints of a "high speed shimmy" that did not manifest itself untill the speedo was buried. Some were my own vehicles - and I have never been accused of babying my vehicles (I even rallied a few of them). I drove my first few cars as if the accellerator pedal was a switch, and 6000 RPM shifts were not uncommon on my old Valiant 6. Sold it with close to 200,000 miles on it.

As for those that failed, and I blamed on lubrication, the failures were OBVIOUSLY lubricant failures when they were torn down, and other than for lack of what I considered adequate maintenance, most were not abused in any obvious way.

You've got to go back to the early seventies, and Polyglycol based lubricants are a case in point. Polyglycols were the first synthetic lubricants to be considered for automotive use, but they never became terribly common or successful, due in part to this incompatability problem.

I never saw them in any automotive stores here in PA, but maybe they were only test marketed regionally. A lubricant not compatible with conventional petroleum oils certainly wouldn't go far in the automotive market.

Matt