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MG Midget and Sprite Technical - Suggested Engine Oil --- Mobil 1 Synthetic.

This is a derivative of another thread (Concentric clutch Slave cylinders) that ended on the subject of Synthetic Engine Oil. =====

I posted -----------------------------
I used Mobil 1 back in the '80s in my Sprite and Triumph Bonneville. It was pretty expensive back then, but I reckon the engines ran better and lasted longer. My then Sprite engine (now my unused spare awaiting a rebuild), did way way way over 100K miles. I wish I'd kept an accurate record. Now oil in general is expensive, and with synthetics giving a longer oil change interval, there's probabably not much in the price difference between a decent mineral oil and a synthetic these days.

I just looked at the Mobil website and they reckon use Mobil 1 Extended Life 10w-60 for older engines. So I've emailed them to get more information.

Nigel had previously written, ---
"I'm waiting to see some fully synthetic on special offer as I think my engine's probably well run in by now ---" - "I sure I'll be told it'll leak through the seals and not be good for the engine despite my experience of fully synthetic for many tens of thousands of miles with my previous MGs --- "

I got a reply from Exxonmobil regarding Mobil 1.

I asked.
-- I own a 1966 Austin Healy Sprite. 1275cc. Back in the 1980's I used Mobil 1 engine oil in it, and I want to use Mobil synthetic oil in it again.
Can you tell me which viscosity I should chose?
I seem to remember that 0/40 was in use in the '80s but can't quite remember. Should I use 15/50?
The normal mineral oil for the car was 20/50.
Thanks L slater.

1st reply,
Dear Sir,
in this case, you can use Mobil 1 New Life 0W-40 which is the current generation of "Mobil 1 0W-40" engine oil.

I asked for clarification.

Please forgive me if I question your suggestion.

My car has an engine design that is MORE THAN 50 years old. --- A Series Austin/Morris.

Are you REALLY CERTAIN, that the MODERN 0/40 oil is correct for a 50 year old engine? I repeat, the original oil specification for the engine was 20/50.

Can you please confirm. Regards L Slater

2nd reply.
Dear Sir, sorry to say, but from your question I understood that in the past you used Mobil 1 0W-40 in your car? ---
"Back in the 1980's I used Mobil 1 engine oil in it. ... I seem to remember that 0/40 was in use in the '80s but can't quite remember." --

Was I wrong?

The main concern with such cars is to ensure seal compatibility with the engine oil used. The point is that the seals usually tend to swell in contact with mineral and to shrink in contact with synthetic engine oil, respectively. In order to avoid potential leaks, I would recommend to stay with the type of engine oil lately used.

If you would really use M1 0W-40 in your car, I wouldn't not have any objections against M1 New Life 0W-40 today.

However, if you used some higher viscosity M1 engine oil (maybe you used M1 Motorsport Formula 15W-50?) you can consider Mobil 1 Extended Life 10W-60.


Kind Regards

So what's the concencus here?

Lawrence Slater

But I think that your mistake Lawrence, was in giving them any sort of suggestions about what you had used and what you thought might work well now. He seems to be overly ready just to follow your lead which makes one a bit suspicious that the individual doesn't really know, and cannot be bothered to check. In retrospect it may have been better at first just to ask and keep quite about your own thoughts and experience.

I think that your logic on the relative costs is sound, and I may be interested in changing back to synthetic again as well. I did use M1 for a while. I don't think it leaked any more than a normal midget engine, but the oil pressure was way down. At the time this worried me but later I realised that a high oil pressure isn't necessarily a good thing. A lower pressure reading can mean a faster oil flow and better bearing surface cooling where it matters.

I guess it would be wise to partially strip and fit new seals when doing the switch over, if the mineral oil impregnated seals have swollen but will then shrink again with the synthetic. Or maybe the opposite is true - having swollen with mineral oil they will now remain swollen and sealing better? Irrelevant in my case as they are well worn all need renewing anyway!

Hi Guy,

I agree, that's why I asked him again, I wasn't really sure he was too clued up either, or just happy to convert a customer lol.

When I used it in the past, my engine was about 20 thousand miles old, and I just drained the GTX and stuck in the M1. I didn't notice any leaking other than the normal weep from the rear scroll. And there is only one oil seal anyway. Timing cover. A series of course.

I can't remember noticing a drop in Oil pressure, but anyway, he is saying that 10/60 would be a good choice as an alternate to 0/40.

I'm due an oil change soon, and as I am also due to strip this current engine, and drop in my rebuilt spare, it will be a good test. If it wrecks the current engine, no problem as I'm going to rebuild it anyway. Worst it can do is leak a bit, and wear out a bit more.

I'm going to telephone an old contact I have in BP and see if he knows more -- if he is still around. (BP had a joint venture with Mobil when I was last there).

Lawrence Slater

I've been running Mobil 1 either 15/50 or 5/50 (dependent on what I win on ebay) in the racer for about 8 years. I've topped up with 0/40 but wouldn't use it for a whole fill. Just bought 10 litres of the 10/60 (again, cheap on ebay) and will be trying that in the next engine.
David Smith

Thanks for that David. When you say cheap on ebay, how much are you talking below retail?
Lawrence Slater

The thicker the better - I have used 15/50 Motul 300V and 10/60 Millers CFS fully synthetic in race engines for years without any problems

Swiftune uses Motul, Bill Richards Racing uses Millers FWIW...

Don't imagine many of you will be interested in Motul Oil when you see the price... :-)

James Bilsland

Possibly of interest...
James Bilsland

I contacted Mobil about use of M1 at sometime in the pasted and I got the impression that the company line was to go with manufacturers viscosity (or thickness or number if I've used the wrong word there)

I also contacted Opie Oils

I'd forgotten it was 0/40 but take your word for it as I only now remember using M1 15/50 'Motorsport' which was freely available from Halfords and the same price as 0/40

as far as I remember oil pressure was the same and certainly no addition leaking

I had a V8 B roadster (conversion) that drank the expensive M1 oil through a Holly carb - a local 'Holley carb expert' had the car for a week at his request, I almost borrowed a Holley carb off a friend of a friend for him to test against, he didn't find the problem and still wanted £100 for his work, I took the car to a rolling road guy (now sadly dead) and he took 15 minutes to figure it out by looking at it and didn't want to charge me a penny because it was such a simple job and he thought he should have realised quicker, a vacuum hose was fitted when it shouldn't have been

anyway back to Mobil - I've used lots of it in the past, used to be £24 for a can but you got a £4 Argos card, then later umbrellas, set of fabric folded suit cases (still got those) then just price increases

Mobil used to issue stamps for service passports too at one time - and probably other marketing gimicks I've forgotten

I'm assuming (always a dangerous thing) that race engines are hotter quicker and don't get used much in the very cold weather so for road cars oil needs to cope with cold weather and less high temperatures ?

that Motul oil seems quite reasonable priced - I had to 'borrow' a litre of oil from a mate when we doing an oil change using his lift and i'd taken the can with less oil than expected when I went to try and find it it was £19 a litre
Nigel Atkins

29.95 for 2 litres of Motul (they only do it in 2 litre and 25 litre containers now..) Perhaps I'm getting old, but upwards of £75 for an oil change seems a little prohibitive... It was about £40 for 4 litres not that long ago...

Oil in race engines tends to run hotter than it would on the road, but I wouldn't be too concerned about running a synthetic 10/60 in the winter - my experience of synthetic oil is that it comes out of the tin thinner than conventional oil to start with...
James Bilsland

thanks for the reply

I think it's an age thing with what seems higher prices, I was going to use Mobil 1 a year or two back but it was over double the price of the Halfords classic oil so I didn't but I think we forget that most things we buy now in real terms are lower in monetry costs than in the past because prices went down so much we notice when they increase
Nigel Atkins

Just read a really interesting book all about oil - 'Which Oil'

I think the original Mobil 1 was 5-50 and this changed to 15-50. I might be wrong and it may have originally been 0-50. In any event the hot end was always 50.

When they first produced the synthetic 0-40 stuff I once bought some by mistake. The problem I had with it was under very hard braking to a stop when the oil gauge would move alarmingly fast towards zero.

I've stuck to 50 being the hot end ever since, and will be ok with the 60 at the hot end.

I used to have really good contacts at Mobil in years gone by but in recent years they seem to have a great product but uninformed staff who don't always bother to reply to e-mails.

I gave up trying to get Mobil SHC gear oil on account of the fact that I didn't want a a pallet load I'd have to collect. I switched to Castrol Synthetic gear oil which has just changed to an improved spec. I haven't checked yet but I think the new Castrol synthetic gear oil is in fact a catch up to Mobil SHC.

Here's a funny clip about oil which I guess says more about me than my choice of oil does:

Daniel Thirteen-Twelve

Lawrence I found a guy selling a load of 5litre cans, I bought two for 79 quid delivered. Mostly on the 'bay it's 40 to 50 for 5l, I've no idea what the high street shopwould charge - other than more !
David Smith

this is £29.99 plus £8 P&P for 5l - you might get discount on P&P if buying two at once but you'd have to ask, says 'factory Sealed Can' -

£49.99 in Halfords

on the American Mobil site there a ‘Which Oil’ calculator
I put in ‘Help me decide’ - 1980 (as far back as it goes) – MG – only choice MGB – total mileage of 25,000 – temp above 0 F – car not under warranty – ‘Ultimate’ – result Mobil 1, Extended performance, 10w-30

tried same but below 0 F and got Mobil 1, Extended performance, 5w-30

they don’t do 10w-60 over there it seems

Nigel Atkins

Mobil 1 Extended Life 10w-60

· Extra seal conditioners to help prevent oil leaks

· Reduces sludge build up to help keep engine cleaner and reduce wear

· Greater oil film thickness for extra protection in older engines

· Higher viscosity to reduce oil burn off in older engines

· More anti-wear additives to help protect worn engines

· High performance basestocks combined with SuperSyn Technology for excellent all-round wear protection
Nigel Atkins

thought I'd post details here for comparision and to save going to links

Mobil 1 New Life 0W-40

Mobil 1 New Life is the latest Mobil 1 generation in the Mobil 1 product family. New Life 0w-40 contains special long-term protection additives which ensure engine cleanliness, prevents the build-up of deposits on critical engine parts and helps the engine retain its value. Furthermore, excellent smooth-running properties lead to fuel savings, thereby cutting CO2 emissions. A plus for the environment.

. For passenger car engines with extended oil change intervals

. Suitable for petrol and diesel car engines*

. Better potential for fuel savings

. Optimum long-term protection for all engines

. Extraordinary wear protection properties

. Rapid lubrication even in very high or very low temperatures

. Reduced CO2 emissions
Nigel Atkins

sorry missed this bit on 10w-60

Mobil 1 Extended Life 10W-60 is engineered for the specific demands of older vehicles – It is specially engineered to provide longer lasting protection in higher mileage engines so you can get longer life out of your vehicle.
Nigel Atkins

and in the Driver's Handbook for (1275) the oil ranges depending temeparatures from 5w/20 to 10w/50 and a lot in between not just 20w/50

(keep getting timed out)
Nigel Atkins

Thanks David.

Also, I've already emailed Mobil again, specifically about the point Nigel made, about the "which oil calculator" only going back to 1980.

I'm awaiting a reply.
Lawrence Slater

at £30 plus delivery I'd bite their arm off, it won't be any cheaper; that wasn't there when I searched the other day... of course!
David Smith

you did note the 'which Oil' calculator going back to 1980 was on the Americian site

the UK one only does Rover MG

you had to add £8 P&P so £38 so only £3 in it :)
Nigel Atkins

Yup, noted that Nigel.

I asked them to clarify "older vehicles", in terms of -- "MG Midget/Austin Healey Sprite from 1959-1979, are not listed at all, or any car from that era", -- with regards to the UK calculator, that only goes back to 1982.

Lawrence Slater

I got the production years a bit out, but they'll get the point I hope.
Lawrence Slater

I'd be surprised if they don't say stick to manufacturer's specification, hence my other thread
Nigel Atkins

Using the information from the ‘Mobil UK Engine Oil Recommendation Tool’

I have come to a personal, non-technical, layman only conclusion for my own use with regard to Mobil 1

as I put in my other thread, 'Engine oil used in UK - 1967 Autocar road test’, when the cars were new 20w/50 wasn’t the only grade of oil used and recommended depending on (what I call) weather temperature

in the Driver’s Handbook it quotes, SAE:-
all temperatures above 10° C (10°F);
10w/50, 10w/40, 20w/50 or 20w/40

-15° to –5° C (0° to 20° F);
10w/50, 10w/40 or 10w/30

all temperatures below –15° (0° F);
5w/30 or 5w/20

and as David Smith had to remind me oils have improved since the 1967 road tests and Handbooks first published

as our cars were too old for the Mobil tool I looked cars with the same engine, these were:-
Rover Group-Austin & Morris
MG Metro Turbo, MG Metro 1.3, Metro 114 Gta, 1.4 Gti, Rover Mini Cooper (1.3i) – all these would be a reasonable match for a standard A-series Spridget

I personally would think that the Midget 1500 with its Triumph engine could be included in the following results

for a road Spridget that’s not heavily tuned and has a rebuilt engine with less than high mileage then Mobil 1 New Life 0w/40 (see earlier post for spec)

all being well it might help cold staring and fuel economy

from Mobil’s ‘Myths about synthetic’ page – ‘If an older engine is in good condition and does not have oil leaks, Mobil 1 provides the same advantages as it does when used in a new engine.’

for a road Spridget that’s high mileage and/or has leaks then 10w-60 Extended Life (see earlier post for spec)

to repeat this all a personal, non-technical, layman only conclusion for my own use with regard to Mobil 1, I might also look at Castrol Edge despite its silly name
Nigel Atkins

This thread was discussed between 23/01/2012 and 26/01/2012

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