High mileage oil question

Two friends have. My local dealer has seen problems with cars over 50K starting to leak afterwards. He sees a lot more cars than I do but either way it's a low percentage. It's still there. No doubt their seals were marginal. Synthetic proved that for them. Personally, I don't swap cars over 50K and I haven't had any issues.

That's terrific. Good testimony for synthetics reducing wear. Doesn't matter much to the seal issue though. That happens quickly if it's going to.

I disagree. They detailed their test and conclusions. Their conclusions were based on their prejudices and opinions and may not agree with yours (or mine). This does not mean their conclusions were wrong. They are just limited. They can and have been extrapolated to other situations where they may or may not apply. What alternate test would you suggest? I have thought about this, and can't think of any test that would not be subject to the complaint that it did not meet real world conditions. I suppose if you randomly picked several thousand new car owners across the US and provided them with free oil with the actual nature appropriately disguised you might be able to draw some conclusions after following the cars for 10 or 15 years. I don't see anyone ponying up the money to run this test. Even CR's less than perfect test sounds hideously expensive.

Unless you are in a really cold climate and make a lot of cold starts/short trips, there is no reason to expect a significant difference in gas mileage if you compare like viscosities. At operating temperature Mobil 1 5W30 and Havoline 5W30 have almost identical viscosities. In typical passenger car usage Mobil 1 is probably a little more stable and the viscosity probably stays more consistent with usage, but I doubt if the Havoline thickens enough with usage to make a significant difference in fuel economy. For like viscosities, the additive package has more to do with changes in fuel economy than whether the oil is synthetic or conventional. The test that is used to determine whether an oil get the "energy conserving" logo compares the fuel efficiency of the oil under test in an engine to the fuel efficiency of the same oil running a PAO synthetic oil. In other words, for the oil to be recognized as "energy conserving," it must show better fuel economy than a PAO synthetic oil. See -

Personally I compared the fuel economy for many miles while switching between Havoline 5W30 and Mobil 1 5W30 in a 1997 Expedition (each oil was run for at least 40k miles). There was no significant difference in fuel economy. It was horrible no matter what oil I used (less than 15 mpg).

Ed

And this will continue...

Do you have anything to base this on or did you just pull it out of something?

Except that oil viscosity is measured using an extremely simplistic test that measures nothing more than pour rate, with a wide range of values stuffed into the standard result numbers. What it has to do with friction is purely coincidental and pretty much inapplicable across technology differences.

Which, is one reason to consider it, however again viscosity !=lubrication value.

Well, personally I have also measured the mileage difference between Castrol and Mobil 1 and get pretty close to one additional mile per gallon. With a bit more consistent oil pressure and slightly less oil consumption when cruising the great basin deserts in triple digit temperatures. YMMV.

I've put synthetic in two different cars, and they immediately started to consume oil at a high rate. But, after topping off, the consumption slowly dropped. One of them was switched back and forth twice, and each time synthetic was put in, it would burn up a quart of oil in about 500 miles (previously no consumption).

Maybe the seal swelling additives in synthetic take longer to act, and you get shrinkage at first when you suddenly take away the petroleum, then they go back to normal after a while. You have to be patient.

But they do seem to have come up with a pretty good system for classifying the performance of motor oils.

They're equally as interested in pleasing the auto makers. The auto makers have an interest in their need to specify performance requirements for an oil to satisfy warranty requirements. Yet per the Magnuson-Moss warranty act they can't specify a given brand. Thus they can specify an API service grade and they and the consumer can be reasonably confident that the oil will fit the bill.

If the oil isn't API certified, all you have is the oil company's word.

If the oil company already has at least one formulation API certified, additional formulations are FREE. Amsoil has several formulations certified. To certify the rest of their product line it would cost them nothing but the price of the tests.

They do test their oils, don't they?

Just turned 250,000 miles on my '84 Civic over the holidays. It's only seen cheap dino oil. The engine has never been apart, and it still burns less than a quart in 3000 miles. The body's shot. The interior is crap. The engine has never missed a beat. Synthetic oil would have been a waste -- especially Amsoil.

If those are high-mileage 4.6L Crown Vics rather than older 5.8 or 5.0 models, they'd get a lot of results on how oil combustion by-products affect the mosquito population. :-)

If Honduh could build a car that wouldn't fall apart around the engine in only 20 years, then synthetic MIGHT not look like such a waste. Except for Amsoil, I agree there!

** True ... and that's enough for me ... depending on the company. The API sets the floor for oils, and that's useful enough, but they have theur flaws ... and that "synthetic" debacle was a glaring one. ** I didn't know that. But still, extra barrier additives (a good thing for most engines) will preclude getting their approval. ** Mobil was pandering to the whims of the API with their SJ Tri-Syn Mobil 1 formula. Pretty crappy at preventing wear according to one lab which sees dozen, possibly hundreds of UOAs every day. ** Yep, some engines (such as Hondas) are known with putting up with mediocre maintenance and even outright abuse and still living a long life. Me? I'd prefer a little cheap insurance. I drove the snot out of my gutless '95 DX Coupe and at 120,000 miles, I was still able to (easily) ** By using a better oil, I figure I was offsetting my propensity for high-RPMs. ** Oh, and what part of "I'm not a fan of Amsoil" did you not understand?? ** Bror Jace

Taking the lazy route and asking you here rather than reading for myself... :-p

Has that been rectified with the latest Mobil 1 oils? In GENERAL (and there's always a risk in being general...) Mobil seems to do a better job than many at providing a consistent product in both synthetic and conventional oils, and I'm a little surprised that one slipped through. Of course, if you risk losing a huge market section because they don't understand that an API rating can be rejected for the wrong reasons.... what is an oil company supposed to do?

I'm pretty sure the SH version of Tri-Syn ... or was it just "Mobil 1" at that time ... had higher levels of ZDDP and seemed very good. Also, the SL versions of Tri-Syn as well as the latest versions of SuperSyn are very good as well. The newest SuperSyn has both moly AND boron for anti-wear additives. There were a few initial batches of Mobil 1 SuperSyn which had no molybdenum and this stuff was really terrible. To this day I don't know if this was a trial formulation or merely a defective bacth but I know of two different peiople in different parts of the country who got some. I'm glad I didn't.

The base oil of Mobil 1 has always been at least good, if not excellent as far as I'm concerned but those two formulations I mentioned above had too skimpy a barrier-wear additive package.

The base oil, no matter how good (stable), can't do it all.

--- Bror Jace

Bror Jace wrote: >

Is there a way to tell which batch you are getting?

- Dave

True, but there's a lot to be said for consistency of base oil. I would suspect that an engine could survive an oil change or two with a batch of oil with missing barrier additives more easily than it could survive a batch of bad base stock. Just a guess- neither is a GOOD thing.

I would

Yes, but thanks to the API (which I constantly criticize) you won't find a bad SL base oil, not in the United States or even Canada. >;^)

--- Bror Jace