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Bill Coburn
Moderator
Username: bill_coburn

Post Number: 1286
Registered: 4-2003
Posted on Saturday, 06 November, 2010 - 05:35 pm:   Edit PostDelete PostView Post/Check IP

Everyone knows that this is the study of the relationship between oils and friction. Recently 'The Economist' published an article on the subject that gives some practical views on modern oils in old motors. The reference is

http://www.economist.com/blogs/babbage/2010/11/tribology&fsrc=nwl
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David Gore
Moderator
Username: david_gore

Post Number: 984
Registered: 4-2003
Posted on Saturday, 06 November, 2010 - 08:08 pm:   Edit PostDelete PostView Post/Check IP

Very interesting article which raises some serious questions about choice of engine oil for classic cars. Technically, I cannot fault the observations made by the author about the reasons for the changing oil formulations in recent years.

My response for our petrol engines would be to use diesel engine oils formulated for older non-turbo charged diesels which contain high concentrations of extreme pressure additives for wear resistance of tappets/cam followers and detergents designed to hold carbon particles in suspension. Due to the longevity and number of normally aspirated low-technology diesel engines in service, these diesel oils should be available well into the future.

I have been using Caltex Delo Silver 15W-40 as a replacement for Castrol GTX2 20W-50 in a Suzuki Swift engine for 30,000Km with no apparent problems so far. Details on this oil are on the following link:

http://www.caltex.com.au/ProductsAndServices/Pages/ProductDescription.aspx?ID=1749

The suggestion of adding EP90 gearbox/differential oil to modern engine oils is interesting however some controlled testing by someone with deep pockets and spare engines over a considerable period of time would be needed to convince me to try this alternative.
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Jan Forrest
Prolific User
Username: got_one

Post Number: 172
Registered: 1-2008
Posted on Saturday, 11 December, 2010 - 06:09 am:   Edit PostDelete PostView Post/Check IP

I've always worked on the concept that it's better to change the oil and filter frequently rather than 'waste' money on fancy expensive "long life" oils. As the early engines (certainly up to the Spirits and maybe beyond) were intended to be run on 20W50 I'm more likely to use this grade or similar and certainly no thinner than 15W40 and change it at 3K miles or 6 months whichever comes sooner.
I can just about see the advantages of adding diff oil to these much thinner oils, but all you're doing is increasing the overall viscosity of the oil which makes the use of such oils a complete waste of time, effort and money.
I don't know if 'viscosity improvers' are still available, but that's all they do - add in a very viscous oil into the mix. Why not just use any (well, almost) cheap oil and change it often to carry away the inevitable contaminants rather try and keep them in suspension where they can only serve to block the filter, opening the over pressure valve and allow the nasties to get onto all the bearing surfaces?
Does this sound as logical to you as it does to me?
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Jeff Young
Experienced User
Username: jeyjey

Post Number: 27
Registered: 10-2010
Posted on Monday, 13 December, 2010 - 09:33 pm:   Edit PostDelete PostView Post/Check IP

Jan, I'm certainly with you as far as contaminants go, although I wait for 5K or 12 months. (But even at that frequency I think the advantages of synthetic are wasted.)

But changing often doesn't address the ZDDP issue; you still need to use a "classic" or diesel formulated oil.

Jeff.

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