Oils, Fluids and Lubricants

[Ian Roberts]

Ok, another question if I may please?

Can you please advise what fluids, oils and lubricants I should use for the following:

Engine Oil
Steering Rack
Transmission
Brakes

If I get a quick answer, I'll pop out to Halfords before it shuts so I am fully stocked up.

Thanks

[taximan]

Halfords classic 20/50, halfords high performance dot5.1 non silicone brake fluid.
Auto box fluid mineral dextron 11. same for power steering.
Rear axle is 1.7 litres of limited slip diff oil.
Shaun.

[Ian Roberts]

Thanks Shaun

[Chris_R]

Engine oil: Castrol 15w - 40 Semi-Synthetic. Or even better, fully synthetic 10w-40 or something like that.

Reason for my argument:
A 20w-50 mineral oil is in fact an SAE 20 oil. It is a mis-conception that it is also a 50 grade oil. It is not. The 20w-50 classification simply means it has been subjected to 2 different tests and met the standards at each test. The high temperature test is conducted at 100c and at this temperature the oil exhibited the characteristics of an SAE50 oil, therefore it passed the classification. It passes the standard for this classification by the use of viscosity improvers. These are long chained molecules that bind the oil together but over time, these molecules break down under the shear stresses in the bearings and the oil starts to revert to the base grade i.e. SAE20.
By contrast a fully synthetic oil is the opposite. It does not have viscosity improvers to break down. A fully synthetic 15W-40 oil is principally an SAE 40 grade oil that behaves like an SAE15 grade oil at low temperatures. What this means is that you get better oil flow at startup, you don't have the same break down issue that you do with mineral oils and the oil will perform better at the engine temperature because that is the natural viscosity of the oil.

[taximan]

synthetics are fine if your engine completely rebuilt, but have cleaning agents in them not compatible with an old oily engine.
Shaun.

[Chris_R]

I would also to a certain extent disagree with that assertion.
An oily engine may have permanent deposits of carbon or sludge built up over time in the oil ways. A bit like clogging of arteries in us humans. Using a thicker weight oil may make pressures go up and that is viewed as a good thing. But the corollary of that is that it could be a lessening of the flow and that could result in accelerated engine wear. Remember, pressure is simply the resistance to flow. The oil pump of itself does not create the pressure, it creates a flow of a certain volume of oil and the resistance in the engine to that flow is what we measure.
The addition of detergents may be of significant benefit and you end up with a cleaner engine running better. Cleaning out old oil and soot deposits can only be of benefit.
I use a 15w-40 in mine, I have pressure of about 75psi on startup, about 50 when running hot and about 30 at idle when hot.

[Keith]

Engine oil: Castrol 15w - 40 Semi-Synthetic. Or even better, fully synthetic 10w-40 or something like that.

Chris, as these modern engine oils quoted above are specifically designed for use in modern engines and will have low or even zero levels of ZDDP (catalytic converter life times are decreased by contamination with Zinc and Phosphates) then what is your recommendation for an oil additive that would make them compatible with our old engines?

Shaun, I cannot get any info on the Halfords oil and whether the formulation includes ZDDP, on their website they state the apparent classification API SE CC which relate to two obsolete classifications for petrol (SE) and diesel (CC) engines and is effectively meaningless.

Castrol Classic Oil With ZDDP Anti-Wear Additive is probably the closest thing we can get to an equivalent high quality oil from the period our cars were manufactured. However there are some lovely (and expensive!) synthetic engine oils out there that have sufficient levels of ZDDP. And synthetic oils do not cause engines to leak oil (unless they were leaking beforehand!). Most synthetic motor oil is fully compatible with modern seal materials and is properly formulated to condition seals, keeping them pliable to prevent leakage.

(ZDDP is an anti-wear additive that is particularly important in valve train protection, in particular associated with flat tappets, overhead cam lobes, buckets and followers and the associated lifters where there is considerable pressure generated at the metal to metal interface - in other words, a Jensen engine!)

One last thing, no matter what engine oil you choose, change the oil at a very maximum mileage of 3000, our engines are not like modern engines!

[Chris_R]

The SE standard dates from 1971. There was no specification for ZDDP content at that time.
ZDDP started to be reduced stage by stage since the "SG" API specification of motor oils and in the "SJ" standard of 1996 a limit of 0.1% was placed in certain classes of oil stocks.
The latest specification is API SN which conforms to the ILSAC GF-5 specifications has been effective since October 2011. It has been recognised that ZDDP is required even in the latest design of engines but it places limitations on ZDDP (to be precise, the limit is on the Phosphorous content which is the harmful part of ZDDP as far as catalytic converters are concerned) of not less than 600 and not more than 800 ppm for the xW-20 and xW-30 grade oils (x = 0, 5 or 10). These are the grades of oils mainly used in the latest designs of engines. Other grades of oil have a minimum of 600ppm however there is not a maximum specified. This is about half the earlier levels. At the moment rumours of zero ZDDP in oils are just that, rumours. If an oil is sold to the latest specification, it will have a minimum quantity of ZDDP otherwise it will not meet the specification.
That does not necessarily mean that an oil manufacturer will include higher levels in their other grade oils, the recipe is a matter of their commercial decision and can possibly only be discovered from datasheets although as Keith points out, that information may not always be published. It may be easier to find out about an oil manufactured by the name on the oil as opposed to Halfords who get it from whom we do not know.
Also it is not clear what level is required for ongoing protection after an initial "break-in" period. There is some suggestion that the lower levels are sufficient for ongoing protection but to date there is a lack of specific research or evidence to support or deny this idea. Most effort seems to be directed towards finding a suitable replacement for the phosphorous component of ZDDP.
Since we don't have to worry about catalytic converters, a higher level of ZDDP can be made by adding it to your oil at the time of the oil change. Frost sell a ZDDP additive that will increment the levels. Generally I take the view that oil additives should not be used but I think this could be an exception.
I wholeheartedly agree with Keith's advice regarding frequency of change but in addition to that, an oil ages over time and deteriorates (I have the facts on this somewhere) and lack of use is bad for the oil especially if the car is basically laid up for the winter months so even if you haven't done as much mileage, an annual oil change is also recommended.

[gladstonematt]

Would the recommendations above be right for a C-V8? (Recommendation copied below as well):
Halfords classic 20/50, halfords high performance dot5.1 non silicone brake fluid.
Auto box fluid mineral dextron 11. same for power steering.
Rear axle is 1.7 litres of limited slip diff oil.


Thanks
Matt

[taximan]

I would say yes as all the same running gear in CV8 (MK111) as MK1 Interceptor. Keith? Chris?
Shaun.

[Chris_R]

Regrettably I disagree with the previous posting regarding engine oils.
I have been studying oils, oil technology and how it works in an engine for some time. I'm trying to put together a definitive article for the JOC magazine but fitting that with work is slow going.
Whilst I don't think I can give a specific recommendation, I would not recommend a 20W-50 oil for any engine in good condition except BMC/Leyland transverse engines where the engine and gearbox share the same oil. They were in fact what the 20W-50 multigrade oil was designed for because of the vicious polymer chop by the gears and previous multigrades were not strong enough. It is too thick at startup on cold and too thick when hot. Yes, it will work and many people have used them for years and years. That doesn't mean it's the best choice.
I certainly would not recommend Halfords Classic or for that matter even Castrol Classic. They are both the most basic of oils that it is possible to get. You want the best lubrication possible even in an older engine. Probably especially so in an older engine. That means you want good flow at startup to get the oil where it's needed as quickly as possible and good flow when hot so that it flows around the engine freely and quickly. You want it to keep the engine clean.
The original specification was for a multigrade. At the time these were typically 20W-30 or at most 20W-40. Unless there is excessive wear, then there is no need to use a higher grade. A higher grade oil (e.g. one that is performing like an SAE50) when hot can in fact have a detrimental effect due to higher friction in the bearings causing higher heat loads.
Personally I would use a 5W-40 or a 10W-40 in any of my engines. Previously I would use a 15W-40 but since I've studied the subject I have moved my thinking to the 5W or 10W grades for better cold start performance. I am considering moving to a 5W-30 but have not done that yet. The original specification on the Daimler V8 for example was for a SAE30 multigrade oil.
It is a matter of fact that a synthetic oil will out-perform any other oil and will stay in grade for life whereas a mineral oil will degrade quite quickly (although less quickly than 40 years ago). So depending on use and age, your 20W50 mineral oil may end up as somewhere between a 20W30 and 20W40 equivalent whereas a 5W40 synthetic oil will remain at that performance all the time. The only real downside to synthetic oils is use in a car with low occasional mileage and where you do not give the engine a chance to heat up properly, the sort of use where it gets used to go 2 miles to the pub on a Sunday and back and apart from that stays in the garage. In these sort of use cases you can get a build up of gummy waxes especially on the piston rings but if you give your car a good using from time to time and get it thoroughly hot through, this problem doesn't arise.
The caveat to using oils such as a 5W-40 or a 10W-40 are in an engine with excessive bearing clearances where the thicker 50 (or even 60) oil will "fill the gap" better than a 40 grade and help to keep the surfaces apart when hot due to the higher viscosity. There is a 5W-65 synthetic oil available which I think would give the best of both worlds - very good cold start performance and maximum protection in an engine with worn bearings.

[Porky]

Might be worth checking out the Millers Oils range of classic engine oils. I have always been a fan of Millers products.

http://www.millersoils.co.uk/automotive ... ne-oil.asp" onclick="window.open(this.href);return false;

They do a Classic High Performance 15/50 which Halfords sell on line. Has high ZDDP according to the info on Halfords site.

Not cheap at £49.99 for 5L, but then nor is an engine rebuild!

[Steve Prince]

I await the final conclusions from Chris and would most likely act upon his advice but the type of oil is not likely to be top of the list of my priorities. The adulteration of fuel however is of significant concern.

[Porky]

Yes I would agree with you on that one. The increased reliance on additives to try and combat its effects seems inevitable.

[Mr.Mini]

Hi everybody ,

On this subject I have a question about capacities for a Interceptor MKII with a 383 ci engine fitted .
Build year is 1970 .

In the original handbook / service book I found the following capacities :

* Engine : 3,8 litres ( with / without oil filter change ? )
* Gearbox : 8.8 litres
* rear axle : 1.75 litres

Especially the engine capacity seems low , and it is not clear the 3.8 litres stated is inclusive/exclusive capacity when the oil filter is changed at the same time .
Also the gearbox capacity seems high .

Can anybody confirm ?

Thank you guys ,

regs Harald

Kind regards , Harald