[ROVERNET - UK]Motor Oil for Old Cars etc.

Fritz Rauschenberg wfritz at mindspring.com
Thu Jun 24 16:07:58 BST 2004

Hi All,
Does anyone have the e-mail regarding the oil filter study that someone did a while
back. I can't find it in my file though I thought I saved it. Thanks in advance for
any help.

Fritz Rauschenberg
Atlanta, GA

Rover1964 at att.net wrote:

> This is an article I encountered in one of the British car club News Letter to
> which I subscribe.  You may find it of interest.  On the other hand, you may
> not.  Regards.
> Fritz
> Hello all,
>      I've read with interest all of the various bits of advice offered to
> our proud new Austin ten owner. And I have found it to be generally good
> advice, and have found a few remarks useful to my own interests as well.
>      But I have to take issue with some of the comments regarding motor oil,
> specifically multi-viscosity, versus single weight oils.
>      I'm astonished by how often I will hear or read someone describing say,
> 10w 40 as oil that is as thin as 10 weight when it is cold, and thickens to
> 40weight when it is hot.
>      To all those who believe this to be true, go and get a quart of 10w 40
> oil and divide the contents, and put them into two glass containers. Place
> one in your freezer over night. The following day take the other and heat it
> to 100 degrees Celsius. Now pour both oils and see which is "thinner."
>      For those who would like to really understand motor oil properties,
> I'll provide a couple of excellent, if fairly technical links at the end of
> this rant, but for those who don't have the energy to wade through it all, a
> one sentence over simplifications is this:
>      10w 40 will become much thinner when it is hot. but it will not be
> thinner than straight 40 weight, if it were hot. Likewise, it will not be
> thicker than 10W would be when it is cold.
>      But as these articles will point out, there is much else to be
> considered when choosing a motor oil. First of all, most of what people
> refer to as the viscosity of an oil, (10w, 30w, etc.) isn't really the
> viscosity, but rather the viscosity index. Similar, but not quite the same,
> and with some important differences.
>      With old engines, and especially very old engines, one of the things to
> think about isn't just simply the viscosity, but also the "barrier film
> thickness." Once again, I'll attempt a criminal oversimplification. Put a
> metal plate onto a tray full of 1/8 inch ball bearings, and slide it around.
> Now do the same with a tray full of 1/2 ball bearings. Both will move with
> nearly equal ease, but look at the distance that separates the tray from the
> plate. Now picture two equally "slippery" motor oils, but one consists of
> much larger molecules than the other? Now which will do the best job of
> providing a lubricating barrier between an old crankshaft and a connecting
> rod bearing, built to 50 year old tolerances?
>        I have heard of several instances where old motors, in good
> condition, even newly rebuilt, were not adequately protected by modern oils
> that had a very high lubricity, but inadequate film thickness.
>      Hopefully, some petrochemical engineer out there will read this, and
> correct my errors, and provide more info. Meanwhile, I will continue to use
> straight 30 or 40 weight oils in very old motors.
>      I do frequently add one quart of 20W50 pure synthetic to a crankcase
> full of straight weight oil, as the ester based synthetic oil will add some
> desirable properties without lowering the overall "thickness" too much. I
> welcome the comments of others on this practice.
>       And on the subject of penetrants for freeing rusted parts, PB Blaster
> is an excellent over-the-counter product, but if desperation sets in, I will
> recommend two even more effective products. The first is KROIL. It's made
> somewhere in Tennessee and it's whole purpose on the planet is to free up
> heavily rusted industrial equipment. The other is available at you GM
> dealer, and is made for breaking loose rusted exhaust manifold bolts, but
> works well for any severely rust-seized part. I haven't bought any of this
> in many years, but it actually has a GM part number, and as I recall was
> very expensive, and worth every penny.
> Automotive Articles .com - Motor Oil Exposed - Choosing the Correct Motor
> Oil Viscosity
> More Than You Ever Wanted to Know ABout Motor Oil
> --
> 1964 Rover P5 3litre Saloon aut
> AACA reg.
> 1966 Rover P5 Coupe manual with
> overd.
> 1973 Cougar Convert. AACA reg.
> 2001 Jeep Grand Cherokee LTD. V8
> ...but OUR Cooking is better than
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