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Synthetic Oil In Classic Minis?


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#1 ImagoX

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Posted 16 July 2007 - 06:03 PM

I developed a bit of an oil leak this weekend - looks like it's coming from where the gearshift shaft goes into the gearbox... I know from reading that this is a common issue, and I've ordered the "upgrade" kit with the new seal, dust cover and rubber bootie to fix it.

While researching this issue however, someone on another forum mentioned that he had leaks in several of his seals, and that switching form a synthetic oil to something made from mineral oil like Castrol High Mileage formula (20W-50 of course) stopped his various leaks.

I got 2 quarts of Castrol High Mileage to replace the oil I'm losing over time, but does anyone out there agree with the assessment that synthetic oil should not be used when I do my next oil replacement? Price-wise it seems about the same for the High Mileage as everything else. My car's a '92 1275 single carb edition by the way.

Thanks!

Edited by ImagoX, 16 July 2007 - 06:04 PM.


#2 *DJH*

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Posted 16 July 2007 - 06:07 PM

Never ever put synthetic oil in a mineral oil based engine!!!! :shifty:

#3 ImagoX

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Posted 16 July 2007 - 06:14 PM

I'm not sure what the previous owner put in... I've mailed him to see if he recalls.

I bought some Castrol synthetic oil which the shop recommended for "frequent starts and stops " (I do mostly city driving) and put in about half a quart to top off what I'd lost since whenever the leak sprung up... Should I change the entire supply and filter before I do any more driving, or just resume topping off with the Castrol High Mileage (which I assume is not a synthetic)? People on other forums seem to use either/or, so I'm not sure what the best oil to use actually is - the Haynes manual mentions Castrol.

On a related note: should I check my level right after driving (when some of the oil supply is up in the engine) or should I wait a while for the supply to return to the sump before reading the best operating level?

Edited by ImagoX, 16 July 2007 - 06:16 PM.


#4 *DJH*

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Posted 16 July 2007 - 06:18 PM

And again, don't put synthetic oil in! the engine seals are not designed for the synthetic oil.

#5 ImagoX

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Posted 16 July 2007 - 06:29 PM

Not that I'm saying you're wrong, but I'm finding a lot of data like this on the web that contradicts that statement - this comes from a guy that works for AMSOIL:

-------------

Synthetic motor oils damage seals.

Untrue. It would be foolhardy for lubricant manufacturers to build a product that is incompatible with seals. The composition of seals presents problems that both petroleum oils and synthetics must overcome. Made from elastomers, seals are inherently difficult to standardize.

Ultimately it is the additive mix in oil that counts. Additives to control seal swell, shrinkage and hardening are required, whether it be a synthetic or petroleum product that is being produced.

( source: http://www.whatprice...thetic-oil.html )
---------------

That said, some people on other forums HAVE reported that an oil like Castrol High Mileage formula seemed to stop leaking, however they were not sure if it was because it was petroleum-based instead of synthetic, or because olls like the High Mileage have additives meant to recondition the seals...

You represent a motorsports organization so you obviously know Minis - what is your judgement based on? What oil would you recommend for a daily-driver type, non-modded 1275? Do you think an immediate oil change is called for, since I added abut 1/2 a quart of synthetic, or should I resume topping off with Castrol High Mileage and then replace the oil with a petroleum-based product on my next change?

I'll still replace the oil seal when the kit arrives, but I'd like to keep it from springing any fresh leaks afterwards, if I can. I know, I know.. "it's a British car", so leaks are inevitable, but... :shifty:

Thanks!

Edited by ImagoX, 16 July 2007 - 06:29 PM.


#6 *DJH*

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Posted 16 July 2007 - 06:38 PM

I'm saying from experience though, i had a perfectly working 1275 ran it for a few months with normal oil, then changed to fully synthetic and within 9 days the engine was kaput.

#7 ImagoX

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Posted 16 July 2007 - 06:50 PM

All of the oil manufacturers claim that synthetics are actually beneficial to older engines, but you obviously have lot of experience and an incident that contradicts their findings... And I have 2 or 3 other accounts of leaks stopping with petroleum-based oil that were there with synthetic. Hmmmmmmm...

Well, that's the beauty of the internet, right? :shifty:

Sounds like I should just resume topping off with the High Mileage stuff and then I'll do a full oil change when I replace the gearshift seal in a few weeks (I'll have to dump the oil anyway). All of the oil manufacturers recommend only using one type of oil and not mixing brands (different additives).

What do you find works best for a non-performance Mini, DJH? I'm more interested in reliability and fuel economy with my '92. Thanks!

Edited by ImagoX, 16 July 2007 - 06:51 PM.


#8 *DJH*

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Posted 16 July 2007 - 07:08 PM

What do you find works best for a non-performance Mini, DJH? I'm more interested in reliability and fuel economy with my '92. Thanks!

I find that a standard 15w-50w or 20w-50w mineral oil to be good for standards. Castrol would be my first choice followed by Duckhams.

#9 ImagoX

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Posted 16 July 2007 - 07:18 PM

I find that a standard 15w-50w or 20w-50w mineral oil to be good for standards. Castrol would be my first choice followed by Duckhams.


Yeah, my Haynes book mentions Castrol by name. Seems like all of the Castrol products you can get here in the US are synthetics, however... Several people have said that the High Mileage formula is great for Minis, but I don't know if it's technically a synthetic or a mineral oil - it doesn't say.

#10 Se7enS1ns

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Posted 16 July 2007 - 07:31 PM

I dont really know how this compares to other oils as its not something i know vastly about, but i personally use the classic car oil from halrauds, im not sure what its called off the top of my head, other even if its synthetic or mineral for that matter, but it comes in a steel tin, painted green and cream, and is for classic, high milage vehicles (it even has a mini on the tin!). Ive never had any problems with it, its doesnt cost the earth, and has "swell seal" in it to aid worn seals. and in all truth, my mini has not lost a single drop in over a year, burnt a bit mind, hence the engine now scattered all over my drive :shifty:

#11 Purple Tom

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Posted 16 July 2007 - 08:49 PM

Been as though you're in Ohio I know it won't be easy for you to get the correct oil for the Mini, but it really is worth the investment.

To be honest its not so much the engine that will sustain damage while running synthetic, it'll be the gearbox. The Mini is notoriously hard on oil, as the gearbox thrashes around completely submerged in it, and the engine then uses that oil, so not only is the oil beaten up by the gearbox, its then squeezed all round the engine at high pressure. Thats why it best to change the oil as often as possible (every 3000 miles or less if feasible) in a Mini, to keep the oil in good condition.

I, like Se7enS1ns, used the Halfords Classic 20/50 oil in my race 1293 engine and it was fine, I changed it every 1500 miles and it ran like a treat, never losing pressure and working properly.

Mini's aren't designed for synthetic oil. I don't know the technical reasons behind this in terms of why the oil is wrong (something to do with detergents and all sorts), but a search will reveal all. Look for posts by Dan, Guessworks or DKLawson on these subjects.

However, I would recommend shopping around for a good quality 20W/50 mineral oil to use in your Mini.

HTH

Tom

#12 minislapper

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Posted 16 July 2007 - 08:52 PM

Look for posts by Dan, Guessworks or DKLawson on these subjects.


Or Grayedout, as he has worked in the oil industry for many years!

#13 Purple Tom

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Posted 16 July 2007 - 08:56 PM

Ooh, has he? I met Graham not long ago, was very surprised to learn he lived about 5 miles from me! Nice bloke too ;D Anyway....tangent over.

Look for posts by Grayedout! :shifty:

#14 ImagoX

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Posted 16 July 2007 - 09:02 PM

Mini's aren't designed for synthetic oil. I don't know the technical reasons behind this in terms of why the oil is wrong (something to do with detergents and all sorts), but a search will reveal all. Look for posts by Dan, Guessworks or DKLawson on these subjects.


I might have at least a partial answer on this one... Got this from a guy here in the States that's generally considered to be something of a Mini guru:

---------------------------

I will throw my 2 cents worth in here -- I have been running regular, non-High mileage Castrol GTX 20-50 in my classics year round for a l.o.n.g time and it has worked well. Many moons ago, there was a guy called Crazy Mike that had worked at Seven Ent when they were still in Virginia and he heavily autocrossed a ratty looking but very quick classic Mini with amazing success. He ran M*b*l* One synthetic oil as he wanted to have the "best oil" he could to protect the engine/gearbox. Sometime after he switched to synthetic, the car started to experience differential failure. He asked the manufacturer of that oil if there was a problem using their synthetic oil in the classic Mini. He got a reply that their synthetic oil was fine in the engine, also in the gearbox, but the shear forces generated in the differential (which uses the same oil as engine and gearbox) would break down their synthetic oil and they recommended he not to use it. I actually saw that letter, so this is not heresay, and ever since, I have not considered using synthetic in my classic Minis."

----------------------------

So... the differential DOES look to be the X-factor here, as confirmed by Mobil... Interesting stuff indeed, and more weight behind my decision to use Castrol GTX High Mileage formula.

Edited by ImagoX, 16 July 2007 - 09:03 PM.


#15 Grayedout

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Posted 16 July 2007 - 09:13 PM

I met Graham not long ago, was very surprised to learn he lived about 5 miles from me!


You might be even more surprised to know that the European technical centre for the World's leading lubricant additive supplier is about the same distance from you and that's where I work !!! :shifty:




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