Modern Oils Not Good Enough ?

[melinx]

An interesting and seemingly well argued case that modern oils may not contain sufficient ZDDP (Zinc Dialkyldithiophosphate) for older engines such as the Carlton ?

Apparently, modern oils have been designed with a lower level of ZDDP in order to prolong the life of the cat.

They argue that the more modern engines use roller lifters rather than the flat cam lifters in our engines which consequently need higher ZDDP levels to cope with the enormous pressures at the cam tip.

                                                       

http://www.zddplus.com/

[man of kent]

New one on me. Never heard of it before. If in doubt I would use molyslip.

[kevinfourlegs]

Same here.

[melinx]

wikipedia : -

"The main use of ZDDP is in anti-wear additives to lubricants such as greases, gear oils, and motor oils, which often contain less than 1% of this additive. It has been reported that zinc and phosphorus emissions may damage catalytic converters and standard formulations of lubricating oils for gasoline engines now have reduced amounts of the additive, though diesel engine oils remain at higher levels.[3]. Crankcase oils with reduced ZDDP have been cited as causing damage to, or failure of, classic/collector car flat tappet camshafts and lifters which undergo very high boundary layer pressures and/or shear forces at their contact faces, and in other regions such as big-end/main bearings, and piston rings and pins. Roller camshafts are more commonly used to reduce camshaft lobe friction in modern engines. There are additives, such as STP(R) Oil Treatment, and some racing oils such as Valvoline ZR-1, are available in the retail market with the necessary amount of ZDDP for engines using increased valve spring pressures. See "external links" in this article. The same ZDDP compounds serve also as corrosion inhibitors and antioxidants."

http://en.wikipedia.org/wiki/Zinc_dithiophosphate

[melinx]

An abstract from page 43 of 'The Oil Bible' : -

http://www.ecoadvanced.net/pdf/motor-oil-bible.pdf

"Basically, ZDTP is used to prevent or reduce engine wear due to metal to metal contact. The higher the concentration of ZDDP in your oil, the longer it will be able to provide this added protection benefit.

In addition, ZDTP also acts as an oxidation and corrosion inhibitor. So, as you can see ZDTP's are
powerful additives that are very important within an oil. Having a good level of ZDTP in your oil helps to
reduce oxidation of the oil, corrosion of engine components and engine wear due to metal to metal
contact.

The level of ZDTP in your oil is listed as two separate components, zinc and phosphorous.
These levels are indicated on some, but not all, technical specification sheets. They will either be listed as a percentage such as .09 or as a ppm value like 920 ppm. These two values represent the same amount of phosphorous in your oil.

API Restrictions on Phosphorous

Current API specifications limit the amount of phosphorous in certain weight oils (0w20, 5w20, 0w30,
5w30 or 10w30) to .10% or 1000 ppm (these are one and the same). This is done because some
manufacturers believe that high levels of phosphorous will prevent catalytic converters from doing their
job for the full 150,000 miles that the EPA requires."

[melinx]

wikipedia : -

"Roller camshafts are more commonly used to reduce camshaft lobe friction in modern engines."

This statement is made in two of the sources of information !

How modern does the engine have to be for this to be valid ?

My 1999 Ecotec X20XEV doesn't have roller lifters

[man of kent]

If what they say is correct and oil companies are advising classic car owners to use their oil, then any damage caused would be a case for sueing the oil company. I'm sure the oil companies know about this and would have made an allowance surely?

Many years ago oil lasted about 3000 miles and now they say 6, 9 or 18k miles dependent upon the filters used. i suspect its a case that there may not be enough of this stuff but the oil is so much better, the engines will last longer.

As I have not seen this before in any automotive journal I'm taking it with a pinch of salt. I think somebody is trying to sell their product.

Its all a matter of opinion. Where's the Molyslip....................

[kevinfourlegs]

On the shelf at your local motor factors  

[carlton_mad]

surely molyslip contains molybdenum disulfide??

now is my memory playing tricks or does this not when hot have a cutting property?? and as such would it not cause accelerated wear??

[man of kent]

Molyslip is super slippery stuff that prevents surfaces touching and generating heat which is what causes seizure. Its much better at providing a barrier. You can also get it in greases and I always try to use this. Running an engine without oil but molyslip on the surfaces prevents heat build up for a while.

Never heard of any 'erosion' of surfaces.

What I dont know is, is Molyslip pure molybdenum disulphide or have they added something else which might be harmful.

[melinx]

The question that occurs to me is; if Molybdenum Disulphide is so good (which I don't doubt) why do the engine oil manufacturers ALL choose ZDDP in preference to it ?

[melinx]

Just found the discussion in the link below which highlights the problems caused by the reduction of ZDDP in modern oils.

The article also hints that it may be beneficial to use a small amount of Molybdenum Disulphide as well as ZDDP !

http://www.memphisbritishcars.org/newsletters/oil200702.htm

[melinx]

The question that occurs to me is; if Molybdenum Disulphide is so good (which I don't doubt) why do the engine oil manufacturers ALL choose ZDDP in preference to it ?

To answer my own question : -

Molybdenum Disulphide is damned expensive at about £30 a pound and would probably at least double the cost of 5 Litres of oil.
It has to be made with a particle size less than about 5 microns or it just gets removed from the oil by the filter because it's not soluble in oil.

ZDDP is soluble in oil and made from considerably cheaper elements.

[man of kent]

Molyslip is indeed very expensive but you do not have to put a lot in the oil. Just a egg cupfull would probably be enough.

It would be interesting if the 20w50 Castrol classic car oil is ok and made to the original spec.

[melinx]

A bit of internet research with some rough calculation indicates that an egg cupfull of 5 micron MoS2 powder would be at least £1 at commercial prices.

Having some experience of the markup on aftermarket sales in this area (about x 10) this would increase the cost of 5 litres of oil by £10

[melinx]

A bit of internet research with some rough calculation indicates that an egg cupfull of 5 micron MoS2 powder would be at least £1 at commercial prices.

Having some experience of the markup on aftermarket sales in this area (about x 10) this would increase the cost of 5 litres of oil by £10

I wasn't aware that molyslip compounds could be soluble in oil, but the company in the link below does oils with it in !

The oils don't look too expensive considering that they are either synthetic or part synthetic !

On balance though, personally, I'm going to stick with Morris Lubricants Golden Film 20/50 Classic Motor Oil

http://liquimoly-direct.co.uk/category/3797-motor-oils.aspx

[man of kent]

Learnt a lot when I worked for Esso........... Also spoke to oil guys at a major auto company.

Basic lessons:-

If it smokes, thicker oil. If the oil pressure comes up slow (oil light stays on for a while) thinner oil. (could be the engine is knackered if it stays on!)
The older the engine the thicker the oil.
Synthetic oils are great and dont breakdown very quickly, they just get dirty.
Semi synthetic a good compromise (longer life)
Older engines were not designed for very thin oils so do you use 5w30 ?? Dont think so unless a new engine.
Hotter climates (high running temps) thicker oil. 20w60 sometimes available!
No additives are needed but no harm.
Running clearances in engines has been reducing with time. (more accurate machining) Hence lower viscocities.

Definitely change the oil regularly. I would say but your decision:-

Normal multi grade such as 20w/50 every 5-6k miles
Semi synthetic such as 10W40 semi every 8-9k miles (prolongs life) But not old engines!
Fully synthetic up to 12k miles. (18k miles only modern cars with special filters)

And of course this depends on the type of use. Town use more frequently (because running temp rarely met). Long runs maybe more miles for the inverse reason.

20w50 is a good choice for most Carltons. Complex engines such as 24v consider molyslip for guides. 10w40 semi is ok for a newish engine.

Its all a bit of your own choice but remember the carlton was designed in the early 70's so use your own judgement whether new oils are suitable. It was designed to run on the 20w50 era.

[melinx]

Seems like excellent, well judged advice

[kevinfourlegs]

Wise words from a clever man.

I would like to add, I've run both my 2.0 8v lumps on 15/40, as per the Vauxhall Carlton handbook. The oil is changed every 6 months, as the car is mainly doing short runs and stop/start traffic. Only do 6-7k annually. When the oil is drained from the car, its a darker brown than it was going in, but never black.

[melinx]

Does the oil you are using contain any/sufficient detergent ?

"The Dark Oil Myth
Dark oil does not indicate the need for an oil change. The way modern detergent motor oil works is that minute particles of soot are suspended in the oil. These minute particles pose no danger to your engine, but they cause the oil to darken. A non-detergent oil would stay clearer than a detergent oil because all the soot would be left on the internal engine parts and would create sludge. If you never changed your oil, eventually the oil would no longer be able to suspend any more particles in the oil and sludge would form. Fortunately, by following the manufacturer's recommended oil change interval, you are changing your oil long before the oil has become saturated. Remember, a good oil should get dirty as it does it's work cleaning out the engine. The dispersant should stop all the gunk from depositing in the oil pan."

An abstract from : -

http://www.nordicgroup.us/oil.htm#Introduction

[kevinfourlegs]

I use genuine Vauxhall oil from the dealer.