Which oil?

[(minisniper)]

Hiya guys
I have another question about oil. I recently did an oil change on Molly and used Halfords 20/50 as I had done before but since then I have been told that I shouldn't use 20/50 in her and I should only use 10/40. I am now very confused as I was told that 10/40 is too thin

Which is the best one to use? Please can someone help!!!

[Admin/Founder 2]

Differcult one to answer really?
i think when a gearbox is new and in tip top condition 10w40 is fine

However i can cause slippage and being thinner is prone to leaking

Had i not just changed the Oil in Boris and had we been keeping him i was going to try a 15w40 grade so you could try that

Most of the Metro Auto Peeps Swear by Morris Lubricants 15w40 so you could try that

i know Molly is low mileage and in really good condition and been looked after so its really just trial and error,you can try 10w40 but make sure its Mineral Oil but to edge your bet play thing safe and meet in the middle and try 15w40 mineral id say

[asahartz]

Accepted wisdom in Mini circles is to only use 20w50, that's what the engines were designed for. Later handbooks only said 10w40 through Rover standardisation. Some oil suppliers have perpetuated this on their websites, but on closer inspection they also recommend atf for the gearbox!
Halfords et al also suggest 10w40 but that's just because they know nothing about classic cars

[notamini]

My handbook for my '69 America says 10W30 or 10W40 depending on temperatures. My valve cover 'Austin' plate supports this.
Since the car was designated for North America, BMC likely standardized it to this market. In those years, all N. American cars used 10W30 and 10W40 when the mileage got to be excessively high or the weather extra warm.
Everyone has their own preferences I think. Whatever makes them happy. Just like the damper pot using power steering fluid in lieu of fine grade oil.

[asahartz]

That last comment got me thinking, as again usual advice here is to use engine oil. So I checked my original BMC workshop manual, and in fact the recommended oil for both is 10w30, but also approving some 10w40 oils and Duckhams Q 20w50. (Also 5w20 below -18 degreesC, something only you Canadians have regular experience of! It's only just stopped snowing in Calgary, and I know it snowed during Stampede last year!)

I'm guessing that the 20w50 advice common here now is because the engines are old, and I suspect that modern oil designations are probably more refined than they were 50 years ago.

So I don't suppose it matters all that much.

[notamini]

Tinkered with the dash pot oil yesterday. I have been using power steering fluid for the last four years.
I actually found a better idle with, get this, gun oil!
Acceleration about the same. No ideas what grade it is. Only reason I had it was from my early years of hunting, after all, I am a Canadian, lol.

[clambod]

As with earlier comments, I'd stick with the 20/50. Other oils are really too thin, especially as the gears run in it. Lower viscosity oils tend to get down the valve guides and get burnt

[(minisniper)]

I'm still very confused about which oil as so many people say different things. I think I might stick to the 20/50 or try the 15/40 and let you know how I get on but she isn't due for an oil change yet so what this space

[Admin/Founder 2]

You cant change the Gearbox in the sump short of a lot of engineering

But ive often pondered i guess that if the Transmission was indeed separate you could put any oil within reason in the engine?

i know when we first got ours and it had wrongly had 10w40 synthetic put in it by the garage the transmission was a bit hit and miss changing gear

but the tickover and the way the engine ran was sweet

If the Transmission could be separated from the engine and ATF used in the Trans but a newer synthetic Oil in the engine i think it would be sweet

i think some of the seal materials would have to be improved on as thinner grade oil will often leak past seals and gaskets on the A series

so practically i don't suppose this will ever happen but hypothetically if it could it would run fine

lets face it engines may of got more sophisticated over the years but the basic engine today is much the same as it always was.

the only reason the oil of today were not specified is they didn't exist back then

if the same engine were built now maybe they would suggest lower grades and synthetic types?

So long as the transmission is in the sump i think we should continue with 20w50 mineral or as an alternative 15w40 mineral which the metro auto owners on here seem to swear by?

Ive never tried it but can see that it can do any harm its certainly not as thick as 20w50 but also not as thin as 10w40

Worth a try i guess?

Huggz
Jodie

[asahartz]

Well further to what I said earlier, with the info taken from my 60s BMC Elf manual, I found a 70s Mini handbook. Which, oddly enough, stated 20w50 for all climates above -10 degrees!

So BMC themselves couldn't seem to make up their minds.

Basically in Britain you won't go wrong with 20w50. Neither will 10w40 do any harm. Just don't use synthetic.

[manuel]

For 7 years I have been using 10/40 in the Winter, (we get down to 10 F deg. sometimes) but in the Spring/Summer (100+ F deg. peak) I was using 20/50, but with over 100,000+ Kms on her and after reading about people using 20/50 in climates that never get as hot as it does here I've bought a couple of cases of Valvoline VR-1 20/50 (non-syn) it states ZDDP on the label.