Synthetic oil

[gungehead]

Hi,
I have just entered the world of classic Jaguar ownership with a 3.8 mk2 MOD.
It is in good nick but I would like to give it a thorough service just for my own peace of mind.
So, can I use synthetic oil in the XK engine?
I was thinking of this -
http://www.millersoils.co.uk/automotive ... r=Classics

It is the correct grade and designed for classic engines with lots of ZDDP.

Has anyone used this oil?

Thanks

Dave

[PPV]

I'll be interested in the responses as I have always used Morris 20/50 oil which is traditional one for classics and found that it does not leak as much from rear crankshaft oil seal. I was led to believe that it also has the right levels of detergent/additives to keep the old girl running well.
Regards,

[Martec]

Hi Dave, we correspond again.

Which oil to use? when you find a definitive answer I would also like to know!

We are dealing with very old engines of very old design that used the oils and technology that were current at the time of manufacture ie mineral 20/50 (not long before it was advised to change at the appropriate time to summer oil and winter oils as multi-grades didn't exist).

Modern engines have less wear (bores will last atleast 200,000 miles) and extended service intervals to keep service costs down (don't agree with that either). They also have very very close tolerances. Modern cars do 12,000 to 25,000 miles a year, I'm lucky to cover 4,000 miles a year in the MkII, so I work on what seems to me best for my use of my old engines. I've been told by Ken to use Millers oils of 20/W50, but previously he said to use a thinner oil as the XK is a very tall engine and it is essential to get oil to the camshaft bearings ASAP on start up.

I don't trust the electric oil pressure gauge so have fitted a capilliary gauge to the lower dash panel ( I compared the electric and capilliary at one point and never the twain did meet) I also compared the pressures when running on a mineral 20w50 and on my present 10w40, exactly the same. So I use a reasonable 10w40 semi synthetic oil and change it at least every year (oil will absorb moisture and allow corrosion) or a maximum of 2000 miles along with the filter (spin on??) to remove all the wear particles. When running on gas it doesn't change colour.

My engine also leaks like a sieve, but I don't have a crankshaft seal either and start up pressure is 80 psi!!

These old cars are a bit of a bugger really, but lovely with it.

Brian

[Ronniebiggs]

All,

Oils are often a thorny issue. They can also be emotive and decisions based on hearsay, prejudice and tradition. I'm therefore conscious I may tread on others' toes or offend their sensibilities, so apologies in advance.

My understanding is as a consumer rather than a manufacturer, so the usual caveats apply.

Modern oils are much better than the mono- and later multi- grade oils available in the Mk2 era. Amongst other benefits they circulate faster, have a more stable viscosity and their detergent additives keep the crud in suspension and thereby keep the engine cleaner.

However...

Therein also lies their downfall. In 50 year old engines there are lots of deposits lurking. The obvious ones are adhering to the inside of the block and the sump pan. The less obvious ones are inside oilways in cranks. Using modern oils, with their more effective detergents, in old engines can 'liberate' these deposits and allow them to travel to critical orifices which they then do a good job of blocking! Result? Catastrophe.

Many years ago, when I was doing some work for Castrol, they convinced me of the enormous benefits of using their synthetic oils. The results of their trials, on a variety of single cylinder test engines derived from well-known manufacturers' designs, were indisputable; synthetics are the way to go. But in an elderly XK, where examples are known to have a reasonable approximation of a total loss lubrication system (i.e. most of it leaks out/is burnt in the cylinders), a low-detergent 20-50 such as Castrol or, dare I say it Halfords, is entirely adequate (other brands are available).

Undoubtedly there will be people who have used modern synthetics without problems. We each need to decide whether to risk the possible adverse consequences to gain the benefits. I work on the basis that, with typically 6000 miles a year and 125 miles to the pint, I want something slippery to keep the metals apart that doesn't cost me a fortune to pour in. I also work on the basis that 6 gallons a year, plus a gallon or so for an oil change, is only £150 which is a lot less than the cost of a rebuild. so is money well spent. The oil is only in there 'on loan' so a fancy formulation is just likely to make the manufacturer richer and me poorer.

There will be those who disagree with me...

Cheers

Jay

[oldtimer]

Dave,
Welcome to the land of classic Jaguars !

Stick with one of the popular 20/50 grades and you won't go far wrong.
Change the oil and filter once a year regardless of mileage which will take away any unwanted contaminants with it.

That regime has served me well down the years

Oldtimer

PS And don't go down the synthetics route for Brake fluid either

[Martec]

I though I should add an extra item to this post on Oils.

Since I first started my rebuilt XK engine in 2000 it has run on 10w40 semi synthetic oil from a local factor, but that factor stopped selling the oil I was using so I made the expensive decision to follow the herd and bought 15 ltrs of Millers 20w50 semi synthetic oil and promptly did an oil and filter change. It immediately felt slower to turn over, I did 240 miles and took it off the road when they started throwing salt about.

I had to replace the diff input seal (a saga in itself) and on trying to start the engine to check for leakage it was reluctant to turn over and wouldn't start (battery on a permanent trickle charger). I put a fan heater under the sump for half an hour and it started instantly! A few days later it only just started when the air temperature was up to 5 degrees.

My engine has only done 40,000 miles since rebuild, has a XJ6 oil pump in the sump (much higher flow rate) and a geared starter, other than that it is standard.

I decided to dump my expensive oil and return to 10W 40 of another make from the local factor, the fact that the 55 year old brass sump plug stripped its thread didn't improve my health and temper (my local BAP bolts supplied new 5/8" UNF bolts). With the new oil in and at 5 degrees it turned over easily and started instantly.

So I'll be sticking to 10w40 for my engine.

I also emailed NGK for the best plugs for my engine, they called back and advised the Iridium plugs I'm using, but from my description of the plugs he recommended moving from 5 heat range to 6 for the heat and corrosion of LPG. As I have two ECU's on the car I am now using BPR6EIX. With the gas flow wound in some it is running really well now. Shame about the noise from one of the front wheels (I think). Investigation tomorrow.

Just a little to muddy the waters............or oil.

Brian

[gungehead]

I thought I would give a little feed back on the synthetic oil.

I refilled the Jag with Millers synthetic oil for classic cars and so far it has performed well. There are fewer oil drips on the garage floor and less oil being used. I don't know if this is because of the oil or that the car is being used more than it was by the previous owner.
Starting is easier, the engine turns over faster, but I have recharged the battery with a modern charger/reconditioner so is it less resistance or more battery power.
I refilled the diff and gearbox with synthetic too and they are both still working fine.

I have used mobil 1 synthetic in my modern car since it was 6 months old. It now has 110000 on the clock and it is still running very well, no noises, no oil burnt, and still performing well. It can only be worth £1000 now at most, but I will still put in the synthetic oil.
So why not continue using it in my more valuable classics? (I also have an MG Midget with synthetic oil in).

I am happy with the oil and will continue using it.

Dave

[Martec]

Hi Dave can you clarify the issue a little for my own benifit by saying what grade of oil you are using and how many mile the engine has done since its rebuild?

Brian

[PPV]

Hi all, I used fully synthetic oil once and found that my rear crankshaft seal poured out oil. Changed back to 20/50 and its back to its normal weep. I have the scroll type seal though.
Hope it does not get worse and I fabricated a drip tray that I have installed and fixed to the car locating using various bolts on the engine.
Regards,

[gungehead]

Hi,
I am using 20/50 oil. This is the stuff -
http://www.millersoils.co.uk/automotive ... r=Classics

I don't know when the engine was rebuilt and I don't know how many miles it has on it. I have done around 1800 miles on the synthetic oil. Not long enough to give a comprehensive answer, but the best information I have at the time and with my resources.

Dave

[wimgohres]

I have been advised not to use synthetic oil by the seller of my MK2 and by my very experienced garage. Because of the lower viscosity my car would start to leak.

Castrol has below text on their website, which I think is quite plausible. This means that the oil should be mineral of semi -synthetic.

The formulations required for modern vehicles are very different from those needed for older vehicles. Oils for modern engines comply with the latest API ratings of SN/CF and specific ACEA and OEM specifications dealing with fuel efficiency, extended drain intervals and aftermarket exhaust treatment systems and are specifically designed for the modern engine needs.

A classic car engine however, can have the opposite characteristics with cork/graphite/rope seals, low pressure gear driven oil pumps, larger oil galleries with greater dependence on "splash" and "cling" lubrication, lower revving with larger machine clearances. Such a widely different engine design can demand a totally different lubricant and the Castrol Classic Oils range offers formulations for older vehicles that have been specially blended for the work they have to do.

Inadequate detergent can result in gums and lacquers clinging to the hotter engine components, and blocking oil galleries – But, too much detergent can cause a build-up of metallic ash in the combustion chambers and piston crowns . In older engines with traditionally high oil consumption, this can cause detonation and pinking.

In older engines where the carbon has built up over a number of years detergents can have a scouring effect, causing the carbon to flake off, blocking up oil galleries and spray jets. High levels of detergent can also "wash" traces of carbon from seals and gaskets, revealing oil leaks where the carbon itself is creating a seal.

Insufficient anti-oxidant and the oil can quickly thicken during high temperature motoring, with large amounts of carbon, gum and varnish clogging oil galleries, filters and piston rings.

Anti-wear additives are added to ensure that if the oil film between moving parts breaks down prematurely, metal to metal contact and irreparable engine damage is prevented.

Engine internals can become pitted with corrosion and rust from acids and water vapour formed during combustion. With the correct corrosion inhibitors, the components are well protected.

Special dispersant additives prevent soot, wear metals and the by-products of combustion settling out in the sump and other areas of the engine, and forming a thick sludge that can block filters and oil ways.

If there is inadequate pour point depressant the oil ceases to flow at low temperatures, with excessive strain on the oil pump or in certain cases, oil starvation on start-up causing complete failure of the lubrication system.

Castrol Classic Oils are specially formulated in the style of the original products, but using the most appropriate and carefully balanced additive technology to provide the best protection and performance for your classic engine.

[Tintin]

What a really useful summary - thanks for that wimgohres, it has clarified some grey areas for me.

Robbie

[340jag]

I first found out the importance of the right oil , with a old sowing machine , I used 3 in 1 oil , in the gears , it more or less seized the machine up , had to wash the 3 in 1 out with WD40 !!