Another great thread, and several great comments. And, as such, they have provoked my thought and rebuttal.

Since posting my last reply to this thread, I have been reading all of the similar threads I could find in the archives. What I have learned are two things: all that damn reading makes my eyes tired, and that where you find a thread about oil on this forum, you'll find several varying opinions, and of course, Larry Bible. BTW, Thanks for the correction about dino&synth combos, I have since found additional info on "blended" oils. I did not know that.

Now, first, I want to comment on this quote from "ocpdba", "Unless we have some direct way of measuring the lubricating abilities of our oil, we must rely on external evidence to make a reasoned judgement about when it is unable to lubricate any longer."

Reasonable, but, the point isn't lubricity, it's abrasion and chemical breakdown. Your oil can and does still provide lubrication when it has arrived at, or passed the point of needing a change. At the point when the oil needs to be changed, the most compelling reasons to change it is that:

The oil has suspended abrasive particulate acquired from outside the engine's environment in the form of grit, dust, and contaminents that have entered through the air intake.

The oil has added abrasive particulate in the form of wear from the internal metal parts that come in contact with each other (no matter how slight, the engine does wear everytime it is started and operated).

Think "honing oil"...

The oil is subjected to extremely high temperature, and sometimes extremely low temperature. And even though it is formulated to handle a certain temperature range, it is never the less, "cooked", and allowed to cool over and over again. This process in itself is not only naturally degrading to the oil and it's additives, but it also will cause water vapor condensation.

Think "deep fat fryer"...

And finally, due to the by products produced from the internal combustion, the solvent properties of fuels, the moisture and other contaminents that have been acquired that are reacting with the additives in the oil, and the further breakdown of those additives through the constant churning in the oil pathways, the oil has chemical reactions occuring within it that have reached a point where that oil needs to be purged from the engine, and a new cycle begun.

Even if you change your oil, air, and fuel filters religiously, you are still going to experience this phenomenon to some degree. The question is whether or not you are going to allow the process to continue past the point where it will begin to degrade the engine further than is "reasonable".

While I have no doubt that the engineers at MB have made their most reasonable recommendations, I also doubt if they would find any fault with the contention that changing the oil sooner is even better.

I also have a problem with the contention that MB is building obsolesence into their vehicles, or any paranoid delusions (please, I don't mean that in a "bad way") about the company going out of business by not doing so. For instance, every day people somewhere in the world are reaching driving age, buying a car, and/or buying an additional car. Look at Larry Bible (sorry Larry), he has 800,000 miles in Mercedes vehicles, and owns several of them, . . . . including a brand new one.

People's needs change, they get married, their kids grow up, the cycle of life continues, and with it, so do car sales. Even if there was a car that was designed to last a millenium, don't you think that people who owned one would buy another, a newer model, a minivan, or a truck version at some point? I have a hard time imagining someone going out of business by building "too good" of a car. Despite longevity, there are too many varied tastes and opinions to be able to build an "everyman's" car.

As for Ford, GM and Chrysler, look at the current models and notice how many of their features are items that have been standard on european (and especially Mercedes), cars. Amber turn signal lamps, smaller padded steering wheels, plush interiors, double-sided plastic-grip keys, rotary headlamp switches (as opposed to the pull-out kind).They've gone "Euro" a long time ago.

When I first drove a newer Taurus a couple of tears ago, I was amazed by how much it's handling characteristics reminded me of a mid-70's 450SEL. The folks in Detroit are building better cars and making them echo the advances that Mercedes has pioneered.

In the 1950's when Mercedes first started importing cars to America, Detroit was building hundreds of thousands, perhaps millions of cars per year. Their first year in this country, Mercedes imported a mere 3,000 vehicles. Many of them are still on the road.

Now, Back To The Oil!

I asked Larry Bible what kind of oil he used, not to be a smartass, but to get a sense of what to use in my car ('82 300SD). When I bought it (back in October), my first thought was about what oil to use in it. As someone who has a great deal of experience with commercial diesels, I was thinking Delo, or Rotella. Checking the service records on the car, I discover that the dealers used Quaker State, and later, Castrol. I am then surprised to find out from the guy who was the second owner, that he has used Mobil 1 for the past 80,000 miles.

I am not certain at this point what the advantages would be of using a "diesel engine lubricating oil" over staying with Mobil 1. The thing I have been told by mechanics about all forms of delo, is that you definately don't want to use it in anything other than a diesel engine, because it will produce entirely too much oil pressure for a gas engine to handle.

Members, Moderators, and/or Administrators, your comments, please...

[Edited by longston on 01-06-2001 at 08:50 PM]

__________________

Scott Longston
Northern California Wine Country...
"Turbos whistle, grapes wine..."