no, unless you want a new gearbox, it will not cope with the extreme
pressures needed in the gearbox, 20/50 mineral is what you need, mini sport
in Padiham where trying to sell me some semi synthetic last week, they said
its designed specifically for the mini, I said but it does not work in them,
they said we have no problems with it, on reading the reverse of the
container it actually said "not suitable for classic minis" :-) but they do
sell a lot of gearboxes, I wonder why.
Sorry guys but I have to say that a synthetic is a better 'lubricant'
than normal mineral oils
the only reason that people seem to think that it isn't as good for a
mini is that the general availabilty of synthetic oils is biased in
favour of newer engines with much higher tolerances for a thinner oil,
such as 0w30 and 5w30 weight oils, if you search around, you will find
that there are some incredibly good fully synthetic oils that will far
outlast and outperform normal mineral oils.
In my humble opinion, I have tried several and will let you know what I
thought of them!
Castrol Magnetec semi synthetic******* Avoid at all costs in a
mini!!!!!!! This oil has shown incredibly bad rates of wear in my
gearbox, It seems to have a lot of detergents or the like which do not
seem to be able to take large torque loads(mini diff pins) don't bother
with this stuff, even if you have the higher viscosity stuff!
AGIP 0w40 fully synthetic, good stuff when warm, gear crash when
cold, slightly smoky on tired engines!
AGIP 10w40 fully synthetic, good stuff, still makes its way past valve stems
AGIP 10w50 fully synthetic, NICE! seems to make the engine run at lower
temps and doesn't seem to cause any problems with gearboxes!
Castrol 10w60 fully synthetic, Very nice, have run it in turbo engines
with no appreciable engine wear over decent mileages, the only reasons
the engines had to be stripped down was because of primary gear
failure(too much torque!)
mineral 20w50 It's ok but after an oil change, lots of metal in oil!!
( never seem to have that problem with synthetics!)
millers transm 20w50 specially designed for minis........ semi
synthetic oil...... haven't had any problems yet, seems to be well
Just be aware that when buying oils for minis you need a decent
viscosity otherwise the gearbox wears like nobody's business, It seems
that most oils are fine with the top end though!
One point of note is that engine temps seem to be an apreciable amount
lower with fully synthetic oils, and synthetic oils aren't as dependent
on engine temp to last for a reasonable time!
I am sure many people disagree with this but it seems to be an ongoing
discussion on the a-series and I am getting a little tired of the
'mineral is better' remarks that always crop up as it is really the
viscosity of the oil and the detergents in it that matter, and
synthetics have a much better service interval than minerals, remember
don't go too thin otherwise you will regret it!
anyway have a look at millers if you are worried as they have done a
lot of testing on their oil and unless you are producing 95bhp+ then I
don't think I would worry too much!
'Optimax is good, Optimax and octane booster is better!'
It is a better lubricant for the engine, but the mini has a gearbox sharing
the same oil, I was told after a gearbox failure at 37,000 mile it was was
because I was using synthetic, I was recomended for normal road use to use
non synthetic only, but I an no expert on gearboxs :-) the guy that gave me
the advice was an expert mini engine & gearbox specialist Bill Richards.
Bit of a Mini myth, this one. (There are lots of them). Mini gearboxes
are not very reliable anyway, particularly when we thrash our cars.
Not uncommon to need gearbox work at that sort of mileage whatever oil
you use. My respected Mini specialist is quite happy with my
preference for a modern synthetic. My friends in Shell's respected
lubricants research division tell me it shouldn't cause any problems.
Coming up to that sort of mileage on my current gearbox now. No
problems so far .
Regards, David Betts
The Mini Gallery:
ok, let us see if we can put this down to some sort of survey so that
everyone who reads this forum can put in their engine size (and peak
torque output if known), mileage, style of driving (slow,average,fast,
looney!) and oil type and viscosity that they have mostly used in their
engine/gearbox, and cause of failure of gearbox/engine if it has failed
at a certain mileage.
I will start with my last engine so people get an idea of what I am
aiming at because we all want to know what is best, and why waste money
on top notch oils if everyone is getting good mileage out of cheap
1330(Normally aspirated 87lbft torque)/48,000miles/looney/AGIP fully
synthetic 10w/60/ Broken crank(ooops!)
we might as well get as many engine sizes and types as possible so come
on I want to see results, and I am sure so do many of you guys!
The mini I had the problems with was a stock 1.3i cooper, which I got new,
until the gearbox problem I was using Mobil 1, after I used millers classic
mini 20/50, what I have been told by various people is that synthetic is
great for engines reducing friction etc but the molecular chain construction
of synthetic engine oils is not suitable for the extreme pressures in a
mini differential & gearbox, I also know a guy who has a track mini & uses
synthetic in it, but he does rebuild his engines & gearboxes every 5000
miles or so, one thing I did notice was how much cooler the 1.3i ran after
switching to mineral, my previous mini a 1380 full race motor with a stage 5
head, sc dog box, 4.1 quaife LSD ran on 20/50 mineral with no problems, but
which ever oil you use mini gearboxes are cheap & readily available should
you have any problems ;-)
Despite their name, most synthetic derived motor oils (ie Mobil 1, Castrol
Formula RS etc ) are actually derived from mineral oils
steve! can I ask which grade of mobil 1 you were using as they do some
really thin ones and some quite thick ones, the only problem is that
the thicker ones are usually special order from most motor factors as
all newer cars don't use them! Yes, it is a good thing that mini
gearboxes are cheap to rebuild, the only thing that gets me is that the
mainshaft bearing cage is plastic and doesn't seem to last long in hot
oil (about 40k) all mg metro boxes I have stripped down at that sort of
mileage needed them replacing irrespective of the oil used, its a pity
that a bearing manufacturer couldn't supply them with metal cages( I
have searched!) it seems that the plastic used to hold the needle
rollers apart becomes very brittle after a while.
Funny you should say about it running cooler with mineral, mine was the
reverse, weird stuff oil!
I agree gearboxes are too cheap to worry about gaining an extra 10k but
a lot of people want to make them a bit less unreliable! ;-)
I don't think that my box will take the superchargers extra torque!!
not 100% sure but I think it was a 15/50, I dont think they had a 20/50
avalable at the time, strange thing is I changed from mineral to synthetic
on my v6 A4 audi & within 2 weeks the car was leaking oil from the rear
crank oils seal, I put it in a specialist & got the clutch replaced at the
same time, a £20 can of synthetic cost me nearly £500 in the end.
There was a thread and an explanation on oils sometime a go.
The suggestion that your mate at Shell says contradicts what I think
Castrol are saying.
Not a Mini but and MGB I rebuilt the engine and gearbox formally using
Castrol XL in both Motor and GB. At the time there was released by
Castrol GTX the ubeut oil so I put that in both Motor and Gbox within
5000 miles I had a rattle in the motor so I stripped it down to find
that the oil had given very little protection and needed new bearings
also the gearbox the bearing were blue. GTX was partly synthetic aditives.
I went back to XL and have used the older formulated oils in old spec
Not sure from the context, but I guess you are referring to me.
Castrol would say that, wouldn't they. Reality is, of course, that
Castrol is a marketing organisation and doesn't make oil atall. All
it's oil in the UK is blended for it by Shell at its Stanlow lubes
Regards, David Betts
The Mini Gallery:
There have been good discussions on this group re synthetic oils.
Why should castrol say that when they have the availability of any oil
Mar 14 2004, 12:49 am show options
From: "tim_lis" - Find messages by this author
Date: Sun, 14 Mar 2004 18:49:47 +1300
Local: Sun,Mar 14 2004 12:49 am
Subject: Re: Synthetic Oil or No
Reply to Author | Forward | Print | Individual Message | Show original |
Check the article below of the DSN classic website (Thanks Steve), this
of course was applied to a question regarding a real Mini and not a 3
door hatchback from a certain German Company
We have met some concern about the use of synthetic oils, in that they
have been attributed to causing low engine oil pressure when hot. We
would like to clarify the situation. To this end, we have contacted
Castrol (UK) Ltd. for their advice and this is their response:
Oil pressure is directly related to viscosity and it is therefore not
the difference between synthetic and non-synthetic oils that causes the
difference in pressure, more the fact that modern synthetic oils are of
a lower viscosity than the A series engine was originally designed for.
Modern, new generation, engines are being designed to run on lighter
viscosity oils to aid lubricant flow when cold and provide less viscous
drag when hot thereby aiding fuel economy. The lubrication system in
older engines is designed to cater for larger working clearances on
crankshaft and camshaft bearing journals, valve gear and other moving
parts, plus oil galleries will be larger and the oil pump will be of a
suitable design to pump oils of a heavier viscosity irrespective of
their base oil type.
Synthetic oils are designed to give greater film strength and higher
levels of lubricity together with increased thermal stability and better
resistance to oxidation. They are also able to maintain their properties
when used under arduous or extreme conditions. These special properties
also enable lighter viscosity, energy efficient oils to be used whilst
offering an enhanced level of protection and performance.
Whilst the lower viscosity of some synthetic oils may lead to reduced
oil pressure, it does not necessarily mean reduced protection. However,
owners who are nervous of a reduction in pressure should consider using
Castrol Formula RS 10W-60 which will give rapid circulation when cold
but will retain a substantial viscosity when up to its full working
We would like to thank Castrol (UK) Ltd & DSN Classics, for their kind
If you Google you will find more references than the above.
My experience was that it made the engine rattle. Thinking back and
looking at the same multi grade, the oil pressure, differed between when
the engine was hot or cold at idle and running. This in turn prompted me
to pull the motor to find that the modern oil did not offer the
protection of the older product.
Just to throw another factor into the equasion, I read an article in a
motorcycle magazine, saying that there are (at least) two types of synthetic
oil; ester based and something else based, I can't remember what the second
one was. One of these (ester, I think) is designed with much tougher long
chain molecules, which apparently resist the chopping action of a gearbox
much better. These are the synthetics specifically aimed at combined
motorcycle engines and gearboxes. Ring any bells? One that stands out is
Motul 300V Competition 15W50 synthetic motorcycle oil. I have not had the
chance to try it, but would certainly give it a go in a Mini engine; I
believe they do a wide range of viscocities, but this is probably the
I would add that my experience with Minis and oils is limited to competition
units that get rebuilt every couple of years after, say, 1000 mile maximum
(rough guess). The oil would be changed 2 or 3 times in this period. As a
general observation over a period of more than 20 years, I would say that
with synthetic oils, the plain bearings often come out looking like new,
other than the odd score mark caused by debris. With good minerals there is
usually signs of wear, and sometimes the journal surfaces are starting to
break up. Synthetics do leak more, and oil pressure drops when the engine is
very hot, but only at tickover. Even in these circumstances, I feel that the
oil is providing better protection. Of the minerals I have tried, Valvoline
Racing 20/50 seems very good, but I would still change it more frequently
than synthetic. In my son's road going standard 850, we use cheap 20/50 and
change it about every 1000 miles. You pays your money, and takes your
Ok just did a quick look and lo and behold 4-stroke motorcyle
synthetics seem to be perfectly happy in a combined engine gearbox
heres a few interesting links
Mobil 1 Motorcycle Oils
Castrol UK/Castrol R4 Superbike
Machinery Lubrication Magazine - lubricants, oil, maintenance
has anyone tried these motorcyle oils in their mini?
The general census of opinion on sythetic oils is that most of the car
ones have friction modifiers in them which don't seem to get on too
well with sliding gears (straight cuts may be ok) and reduces the oil's
effectiveness under high pressures, as most bikes have a combined sump
on them they seem ideal for comparisons with mini engines, 1300
hayabusa anyone? what oil is recommended for that?
Because they still make lots of money sellng cheap old 20/50 to
classic car owners .
I have no problems with people who wish to carry on using it. All I'm
saying is that the arguments against synthetics aren't gospel.
Regards, David Betts
The Mini Gallery:
Not a mini - but I do have an A series engine 1100 cc, and I have been
using Duckams 20/50 with no problem. Cheap 20/50 seems to fall out much
sooner (my car has done over 250,000 miles)
Castrol do a Classic 20/50 in a can available from Classic car people -
but I don't think there's any difference particularly. Castrol own