MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Ribcase Alternative Oils

Following on from the thread on diff oils, has anybody tried this from Mobil for the gearbox in lieu of 20/50 :-

http://www.mobil.co.uk/UK-English-LCW/heavydutyoils_products_transmission_mobilube-xhp-75w80.aspx#

I'm in need of replacing my Ribcase gearbox which seems to have layshaft wear - I know of the recent poor layshaft quality - this one was built about 4 years ago but is still very low mileage.

Are rear seals likely to be an issue ?

R.
richard boobier

Richard am I missing something in that link, is there anything specific about the Mobil 75/80 gear oil that suggests it's a good substitute for the 20/50 engine oil that has done the job for 50 years? (or to put it another way, why would you?) Peter May does decent layshafts.
David Smith

( 75/80 gear oil)

That would be the secret ingredient right there.....I think that the oil would be alot thicker and would provide a better gap filler in worn parts ...is it to thick? If it goes bang leaving parts all over the road, then id guess so.

On my rib case I used lucas oil stabilizer treatment ...about 1/2 qt and that did the trick, it really quited down the noise to a very tolerable level.


Prop
Prop and the Blackhole Midget

The last layshaft I had from Peter May went back because the oil way drillings were missing. SO it seems that even his quality control is seriously suspect ! But they did agree to refund without any quibbles at all, so the problem was obviously known!
dominic clancy

David,

My point is oils have moved forward significantly in the last 50 years and are one of the major factors in the improvements in engine developments and durability that we see today - BMC did not have available 'in the day' oils such as are available now.

Therefore if improved oils are available specifically tailored to work in gearboxes (as apposed to general purpose motor oils) why nor use them ?

Prop,
Why use an oil and then add an 'improver ?' treatment to it if better oils may be available ?


R.
richard boobier

I've been wondering about this, it would make sense that a gear oil might be better than an engine oil for the gearbox.

I can accept that back in the day 20/50 as made in 1965 was good enough (did the cars actually have a warranty period back then, if so was it 6 months ?), but I don't think we can buy 1965 spec 20/50 oil and any oil we do buy has probably been modified to run better in an engine, with no thought to small number of cars running it in their gearboxes.

Grab from wikipedia....

PI Category GL-1 (inactive*) designates the type of service characteristic of manual transmissions operating under such mild conditions of low unit pressures and minimum sliding velocities, that untreated oil may be used satisfactorily. Oxidation and rust inhibitors, defoamers and pour depressants may be used to improve the characteristics of lubricants intended for this service. Friction modifiers and extreme pressure additives shall not be used.

API Category GL-2 (inactive*) designates the type of service characteristic of automotive type worm-gear axles operating under such conditions of load, temperature and sliding velocities, that lubricants satisfactory for API GL-1 service will not suffice.

API Category GL-3 (inactive*) designates the type of service characteristic of manual transmissions and spiral-bevel axles operating under mild to moderate to severe conditions of speed and load. These service conditions require a lubricant having load-carrying capacities greater than those that will satisfy APL GL-1 service, but below the requirements of lubricants satisfying the API GL-4 service.

API Category GL-4 designates the type of service characteristic of spiral-bevel and hypoid gears in automotive axles operated under moderate speeds and loads. These oils may be used in selected manual transmission and transaxle applications.

API Category GL-5 designates the type of service characteristic of gears, particularly hypoids in automotive axles under high-speed and/or low-speed, high-torque conditions. Lubricants qualified under U.S. Military specification MIL-L-2105D (formerly MIL-L-2015C), MIL-PRF-2105E and SAE J2360 satisfy the requirements of the API GL-5 service designation.

API Category GL-6 (inactive*) designates the type of service characteristic of gears designed with a very high pinion offset. Such designs typically require (gear) score protection in excess of that provided by API GL-5 gear oils. The original API GL-6 test equipment is obsolete.

API Category MT-1 designates lubricants intended for non-synchronized manual transmissions used in buses and heavy-duty trucks. Lubricants meeting API MT-1 provide protection against the combination of thermal degradation, component wear, and oil seal deterioration which is not provided by lubricants meeting only the requirements of API GL-4 and API GL-5.


From that I'd guess a Spriget box is GL1 - but a nice new synthetic GL4 is looking good ??

Thoughts ?

Malc
Malc Gilliver

Hey richard,

"Prop,
Why use an oil and then add an 'improver ?' treatment to it if better oils may be available ?""

Simple... ignorance is blissful

Prop
Prop and the Blackhole Midget

I'm collecting a refurbished ribcase from Heathrow transmissions on Monday. It will be interesting to hear what they recommend!
Phil
P J Dent

Looking a little more into 20/50's and note that Millers make an oil with some EP properties for use in combined engine/gearboxes :-

http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=10355&SortOrder=1

So they are noting a need for better protection for gears etc.

Also the newer 20/50 Penrite oil I have has now increased the API rating from SG to SL from the previous can I bought.

Penrite also list GL3 gearbox oil for where engine oil was originally spec'd. 30 and 40 grades.

http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=18985&SortOrder=1

There 'selector' suggests a 30W grade.

I'm also having my spare box rebuilt, so want to give it the best chance of lasting a bit longer than the current one !.

R.
richard boobier

75W/80 or 75W/90 gear oil is roughly the same viscosity as a 10W/40 engine oil, so no advantage with 'filling gaps'!

If a gear oil is used, it must NOT be an 'EP' type or the 'yellow metal' components like synchro rings will get slowly eaten away by the oil.

Richard
Richard Wale

no-one's mentioned the history yet, maybe it's not known or been forgotten. The point is that the ribcase gearbox was actually designed to use engine oil. In the late 50s when Issigonis designed the Mini, one of the many problems that had to be overcome was how to allow the engine and gearbox to share a common sump of oil. Once this was solved the design was carried over into the inline ribcase box in the early 60s. It seems to me to use anything other than what it was designed for is asking for trouble. A properly built and maintained ribcase will do at least 60 - 70k miles, and some far more. I suspect your issue with a 4 year old box lies elsewhere...
David Smith

" A properly built and maintained ribcase will do at least 60 - 70k miles, and some far more"
Depends how you use it. For road use yes, but for autotesting nowhere near as long before 1st gear gives up :-)
Though to be fair one autotest is a year's worth of driving in first for many.
Paul Walbran

For what its worth, Hardy Engineering

http://www.hardyengineering.co.uk/

used 20/50 in the gearbox they recently rebuilt for my track Ashley midget.
D Plumb

I have only ever used 20/50 in the last 30 years with no issues. This included my race car. Regular changing is key for longevity in my view.
Bob Beaumont

Agree Bob, not playing top trumps but it's over 40 years for me, +100k commuting, autotests, classic trials, sprints, hillclimbs and racing.
David Smith

the fact that 80/90W gear oil and 20W50 motor oil have about the same viscosity is a red herring

If it mattered, then we'd all use 80/90 gear lube in our engines, or vice versa.


The point is that oils are formulated for a purpose, and using the wrong type of oil means that important additives and characteristics will not be present, and wear or other troubles can result.



Norm Kerr

taking on board David Smith's, unusually lengthy, post which informs of the original design from the Mini then even though the the box doesn't exactly have the same use in the Mini compared to Spridgets, as a poster has put on the B forum, wouldn't it be that the oil for the shared Mini engine and g/box would be a better choice than the standard engine oil?

I was also disappointed to read that you might only expect 60-70k-miles out of the box before it needs a rebuild (although you could get a lot more)
Nigel Atkins

I've also been running A and B series since the sixties,
and have noted how all the oils sold have changed and improved over the years.

Simply restating 20/50 is only quoting one parameter of the oils complex make up. Oils in the 60's were SD ish grades, now the 'Classic' mineral 20/50's are well up in the SG/SL specs - much enhanced specs.

Had BMC had more modern oils available i'm sure they would have spec'd them.

Modern 20/50 can have additives that make it more suitable for gearbox use without attacking 'yellow' metals etc - as per the links I posted.
Not all 20/50's have the same additives - clearly the oil manufacturers see a need to produce special 20/50's for mini's where gears and engine share oil.

So would the ribcase not also benefit from the 'mini' oil also as it has many similar components including needle bearings etc as David noted - if you can further reduce wear without causing any damage why not ?

I will try and ring Millers as I believe they have a tech line number.

R.




richard boobier

Richard,
I agree with you oils and their packages of additives have changed - taken the current fashion for excessive ZDDP when other anti-wear ingredients will cover this plus the lower level of ZDDP in some modern oils is sufficient anyway

some varying views in the following links -
http://www.kewengineering.co.uk/Auto_oils/index.htm

http://www.carbibles.com/engineoil_bible.html

http://www.mgb-stuff.org.uk/enginetext.htm#oils
Nigel Atkins

Interesting reading

the first link is pretty general. It essentially summarizes with "he doesn't know", at the end of his summary section.

the second link is very detailed and complete. It clearly states the need for ZDDP for older, flat tappet engines (read the section titled, "The Question of Phosphorus and Zinc"). It also lists the different categories of oil over the years (a useful point of reference, but, sadly did not include the ZDDP levels, or other additives, for each one).

the third link clearly states "SJ" is as 'modern' as you want to go, when choosing oil for these engines, because of cam/follower wear concerns (he includes a cautionary tale). Lots of great reference information included.



Norm


Norm Kerr

Norm,

Further more concise info on Zinc/ZDDP from Penrite and API ratings.

http://www.penriteoil.com.au/tech_pdfs/169%20ZINC%20MYTHS%20AND%20LEGENDS%202010%20UPDATE.pdf

If you use their oil selector it gives further reading.

R.
richard boobier

Well that link does not seem to work.

Go to Penrite AU main site,
Technical,
Engine oils,
item 169 zinc myths and legends 2010 update.

R.
richard boobier

Richard
"clearly the oil manufacturers see a need to produce special 20/50's for mini's where gears and engine share oil."
Do they? Do you have a source or reference for this please? When we had a Mini in the family we used Duckhams or Castrol 20/50 - same oil as any other car needing 20/50, Fords etc.
Much of the advertising matter for modern expensive 'special' oils for classic cars is just marketing hype based on FUD (fear, uncertainty and doubt). If anything they leave modern additives out so they should be cheaper.
David Smith

David,

As per my 3rd post !

http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=10355&SortOrder=1

R.
richard boobier

I have a manual Rover SD1 Vitesse, they were factory filled with ATF because that's what the factory had, everybody at Land Rover knew the oil was sub standard and it took until about 1999 for them to change to Texaco MTF, I remember taking to the Texaco oil rep about it.

As for statements like - the gearbox was designed for 20/50, I can't argue with that, because it was from before I was born, but my own dealings with LR, Jaguar, Bentley, Ford and others seemed to follow a standard path.

If it was good enough, leave well alone.

Trouble is good enough was always specified as "do we have a large warranty problem ?"

I remember reading a print some one had left on a printer at MG Rover comparing the warranty cost of the K series head gasket failures and the on cost to MG to fix the problem, they choose not to as it cheaper to pay the dealers for warranty than fix the head gasket, and look how that turned out !


"From: Norm Kerr Michigan USA on 24 September 2014 at 11:48:12 (UK time)
the fact that 80/90W gear oil and 20W50 motor oil have about the same viscosity is a red herring

If it mattered, then we'd all use 80/90 gear lube in our engines, or vice versa.


The point is that oils are formulated for a purpose, and using the wrong type of oil means that important additives and characteristics will not be present, and wear or other troubles can result."

Not true, a modern engine has the thinest possible oil that keep it alive for the warrant period, why the thinnest ? cos then they can quote better fuel consumption.



From: Bob Beaumont Greater London United Kingdom on 24 September 2014 at 10:51:42 (UK time)
I have only ever used 20/50 in the last 30 years with no issues. This included my race car. Regular changing is key for longevity in my view.

Bob, how often do you change you oil ?

Malc
Malc Gilliver

Richard,
"clearly the oil manufacturers see an opportunity to spread FUD and charge an extortionate amount for something not actually needed." Which is what I meant by marketing hype. Millers charge 50% more for the Mini stuff than their normal Classic 20/50. There was no special 20/50 in the 60s, 70s and 80s and IMO no need now either. I hardly think they would have built and sold over 5 million of them if the gearbox oil spec was fundamentally flawed.
David Smith

Norm,
I learnt a while back on here that belief systems are so strong they can rarely be changed but your summary of the three links I put up has me puzzled - I put up the three to show the discrepancies (or differing beliefs)

you should note that the first link is to an oil expert and the other two are not, they are good web site compilers and their sites contains loads of good information but they are not experts on oil

just for the obsessional need for ZDDPZZTop put together the information from the Penrite link and what is on the oil expert's site - a brief extract I've just put in another post -
"The fact is that the levels of ZDDP in modern oils are still sufficiently high enough to protect most classic engines, and today’s oils still have as much as 4 times the amount of ZDDP by comparison to oils formulated in the early 1960s when the A and B Series were first used in production cars. Whilst newer engine designs differ from older designs, the newer oil formulations more than compensate for wear protection by having differing formulations for AW protection."

http://www.kewengineering.co.uk/Auto_oils/oil_additives.htm
Nigel Atkins

David,

I am not an oil expert and can only read /research / follow what the manufacturers suggest,being open minded and without being totally wedded to the past.


If you follow the Penrite selector for the Midget they recommend a 30 grade GL3 which costs similar to their Classic 20/50 - as per Moss cat.

My personal experience with BMC/Leyland combined engine/gearboxes in my company cars 'in the day' was not good - transfer gears eating casings and total unit failures etc. I don't recall any other manufacturer following this idea regardless of how many were produced - even some of the later Leyland units had separate engines / gearboxes.

It will be interesting to strip my current box and see what has worn. Previously I remember my ribcases in my everyday drivers doing many more miles - even driven enthusiastically before needing attention. However if modern lub's can help durability - I'm all for using them.

R.

richard boobier

Malc

I change the gearbox oil every 2 years. I tried to follow the original frogeye handbook recommendations. I followed this advice even though the later handbooks indicated something longer. I used to change the race car oil every other race. I ran 4 seasons of modsports without any gearbox failure.
Modern oils may be improved but given the quantity involved and the ease it can be changed it seems easy to carry on the practice.
Bob Beaumont

Found this recently posted on the MGB Tech board running a similar thread.

Its Headed MGB/GT. dated 1975.

Does anybody know if there is a reference source for all of the Technical Service Bulletins issued ?

Shame the 'good book was not updated as well' for any service bulletins !

R.


richard boobier

I'm sure some people, maybe even everybody already knew this, but it came as a shock to me.


20w50 engine oil is about the same viscosity as 75w90 gear oil !

I didn't know they used different scales !


Malc




Malc Gilliver

Malc,
do bear in mind the numbers are within a range and viscosity (range) is only one thing to consider

BUT - I'm hurt

have you never seen or taken notice of the chart I've frequently put up in posts and threads

really !!? never!!??

next you'll be saying you don't know anything about a (the) 'good book' !!!!!!


this one being full range and in colour is easier on old eyes




Nigel Atkins

Nigel,

I see what I look for, not what I'm looking at ! (there is an exception to this rule, but as summer is coming to an end there will be less of the exceptions!

But thanks for your pretty coloured in version, it is easier to read !

Malc
Malc Gilliver

Malc,
don't worry I can't read or right proper cos of my eyes (and perhaps brain if it's still there)
Nigel Atkins

I have read information about EP additives and yellow metal attack, due to the copper content being attacked primarily by sulpur, and there are standard tests for it. It seems some EP additives are more of a problem than others and temperature is also an important factor in the reaction rate. The spridget final drive uses EP oil and that uses copper based alloys for the diff bearings, unless you are unlucky enough to have a late diff with tufnol sun thrusts and then the planets still have copper based bearings. IIRC the GL rating is an important factor, this article seems to give some decent information http://www.widman.biz/uploads/Transaxle_oil.pdf , so looks like GL4 maybe OK but not higher. Other than that search and find lots of differing opinions.
David Billington

I have 3 ring binders of MG Service Memoranda and Service Bulletins but unfortunately nothing later than 1967... and nothing on gearbox oil.
David Smith

This thread was discussed between 23/09/2014 and 29/09/2014

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.