22 replies to this topic

[Cooperman]

I actually don't know of anyone using a synthetic in their classic MINI.
I for one wont be using it...yet....
As suggested ( proven ), a quality mineral oil of correct weight works well in the shared components of a MINI.

Since finding out GTX no longer contains the ZDDP levels as before, I've been using GrandPrix 4 Stroke 20/50 motorcycle oil. No issues. ( Can't get the VR1 here )

I do recall...but not where....reading that synthetic should NOT be used in a MINI due to the shared gear/engine design.

I had always thought this, but what 'richard1' says is very interesting.
When mine was damaged when i used a synthetic my old friend who used to do my machining said that if I used 'weasel p**s' in my engine what did I expect. His belief, and one I think I share, is that the manufacturing clearances are larger in an A-series than in a modern engine and a thick mineral oil fills in the gaps better.
Maybe synthetics have moved on and a 'thickish' one would be OK even for high internal stress levels in the gearbox. I don't know whether to risk it as a blown up 1310 cc 1964 Cooper 'S' engine with around 115 bhp and SC CR box would be very expensive to re-build.

[Richard1]

The myths that you can't use synthetics just that. The problem is that people tend to group comments without details. Almost all synthetics on the market are made for gasoline autos. That means low ZDDP. I get emails every day from people who believe Mobil1 is the best. It may be good for gasoline engines (although my son lost both turbos in his Audi S4 using it) but it is not what we want in flat tappets or shared compartments. The zddp remains in diesel oils, so that is the easy way to go, but the only commonly available diesel synthetics are 5W-40, which is becoming the oil of choice for big rigs. The comment above about a Shell synthetic is typical. No name, viscosity, or API rating. What makes it hard is without looking at the msds sheets, it is hard to tell a group III synthetic from a group IV (PAO). It is also harder to fine any synthetics that run into the SAE 50 range.

I have Group II oils that will hold up 700 hours or more in many diesel engines. But put it in certain Deutz engines with gear driven cams of a specific diameter and it shears down around 300 hours. It is like a mill, grinding down the polymers.

Chevron's Delo Synthetic is an excellent oil, but it is a group III and I have oil samples where it shears. So I respect and look for group IV synthetics with all the zddp of a good diesel formulation. The Castrol product you mention has the additives. Even more than a CI-4, so that is good for transmissions and flat tappets. Those come into play in sliding action. That helps reduce wear when the oil is scraped off (by gear movement, tapped sliding, etc.) or when the oil has sheared and doesn't, for the moment, maintain hydrodynamic lubrication. The best test we can have of this is the used oil analysis, looking at viscosity for the permanent shear, or lead content for temporary shear (pressure in the bearings).

This is not to say mineral oils are bad. I run Group II mineral oils in a dozen cars and trucks of mine. I run a Grupo IV synthetic in my 88 BMW, and will put it in my Corvair at the next oil change (now that it is broken in).

But I run CI-4 in everything that does not have a catalytic converter. And a group II/group IV API SN blend in those with catalytic converters.

[Cooperman]

Richard, could I ask what you feel would be the best oil for a Cooper 'S' Mk.1 with a straight cut gearbox and straight cut drop gears used for rallying. Bear in mind that the oil would be changed after every event and would never do more than 500 to 1000 miles and usually less. The engine will be revved to around 7000 maximum with high oil temperatures at certain times. There would be very high and frequent load reversals on the gearbox and final drive.

[Richard1]

Richard, could I ask what you feel would be the best oil for a Cooper 'S' Mk.1 with a straight cut gearbox and straight cut drop gears used for rallying. Bear in mind that the oil would be changed after every event and would never do more than 500 to 1000 miles and usually less. The engine will be revved to around 7000 maximum with high oil temperatures at certain times. There would be very high and frequent load reversals on the gearbox and final drive.

With those extremes, something like the synthetic version of the Castrol VR1 racing is probably in line, probably better yet in the 10W-60. For the trans you want the viscosity and a high zddp value. Going synthetic for very short events might seem like overkill. That depends on the budget, but with it you have more protection. Just don't get conned by adds like Mobil1's 15W-50 that claims it has extra protection for flat tappets, but then is an SM, so obviously doesn't. Your application might also be one of the only ones where I'd think about adding more zddp. Normally I'm totally against it, but it can help the transmission, and you are changing early enough to not worry about the lack of detergency. If going that route, I'd go with an oil that tells you it's phosphorous content and a zddp additive that also tells you. Don't let your final formulation get over 1800 ppm of phosphorous or you could have cam galling.

I run my 5W-50 CI-4 in a buggy that I sponsor here. We actually only change the oil every 5 or 6 races. Took first place last season. We upgraded to a Vtec this year, so we will run in a different class.


Obviously this is not a shared compartment. It is a Honda 1600 that runs about 7500 rpm through the dirt tracks and roads.

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Edited by Richard1, 02 April 2011 - 05:34 PM.

[John Clayton]

Thanks very much to everyone for the advice -most impressed at the level of expertise of Mini Forum members!

Would my oil cooler need to have a Thermostat? I've heard that (if I recall correctly) the Thermostats you can buy aren't set to the optimum temp for Mini oil in a competition vehicle (Pitstop @ Brize Norton -Mini Se7en racing gurus).

For info, here's a summary of the oil I currently have in the Mini -how often do you think I should change it? I know some people change it based on number of events, but a Sprint/Autosolo is hardly any mileage whereas a Rally/Track day is many times longer so it would probably be safer to change it based on 'competition miles' or even 'competition minutes'

http://www.millersoils.net/1_Millers_frame_MOTORSPORT.htm
Engine Oils
CTV 20w50

DESCRIPTION:
Very high performance semi-synthetic competition oil for engines which have their transmission in the sump such as the original Mini.
Extra high performance engine oil based on the highest quality performance additives and shear stable viscosity improvers in synthetic and mineral base.

APPLICATION:
Competition use on vehicles where the engine and transmission share the same oil.
Especially suitable where a limited slip differential is used.
Also suitable for all gearboxes which specify a 20w50 engine oil.

USER BENEFITS:
� The semi-synthetic base fluid formulation and special additive system provides maximum engine protection along with transmission performance to API GL4 level, the normal performance level demanded for gearboxes.
� Also suitable for conventional engines which have heavily loaded skew gears, often due to running high oil pressure.
� The incorporation of synthetics means the lubricant has flow rates close to many 15w grades, helping to reduce drag and increase power output without any detrimental effect on centre main bearings.
� Viscometrics reduce oil consumption, making this oil suitable for long distance racing.
� CTV has a formulation with a viscosity at the top end of an SAE 50 ensuring oil pressure will be maintained under arduous conditions.

PERFORMANCE PROFILE:
� All competition and highly tuned derivatives of original Mini.
� Also suitable for other highly tuned vehicles with shared engine/transmission oil including motorcycles.

TYPICAL CHARACTERISTICS:
SAE Viscosity Grade ... 20w50
Specific Gravity @ 15�C ... 0.885
Kinematic Viscosity @ 100�C ... 21.0cSt
Kinematic Viscosity @ 40�C ... 170cSt
Viscosity Index ... 146
Pour Point �C ... -15
Flashpoint �C ... 215
Cold Crank Viscosity @ 15�C ... 9,500cP

HEALTH AND SAFETY:
Health and Safety Data Sheet 5492 applies to this product. When used for the purpose recommended and with due regard to the appropriate Health and Safety Data, the product should cause no concern. If in doubt, consult with Millers Oils Technical Department.

[John Clayton]

P.S. I found the following in my notes on the car...


Millers recommend changing CTV 20/50 oil every 3 events [so this would be about 120-165 track minutes if it was a race or a single venue rally car]. However, you can send a sample [what quantity and how packaged?] back to them and they will test it free of charge to advise how much life it has left in it.

Most oils are designed to run at 90-100C but they will be OK at 110-120C before they start to hit problems. Millers aren't sure what temp my engine (or indeed Minis with Oil Coolers) are likely to be running at.

[Gulfclubby]

Running a similar engine to yours but with an oil cooler installed and have never gone beyond 90°C on the oil temp. Mind you, I'm not racing or rallying the car though. I'd say, given that the installation and the price of a decent mid-size oil cooler don't ask for much, it's a fool-proof improvement for any tuned engine.

[Richard1]

P.S. I found the following in my notes on the car...


Millers recommend changing CTV 20/50 oil every 3 events [so this would be about 120-165 track minutes if it was a race or a single venue rally car]. However, you can send a sample [what quantity and how packaged?] back to them and they will test it free of charge to advise how much life it has left in it.

Most oils are designed to run at 90-100C but they will be OK at 110-120C before they start to hit problems. Millers aren't sure what temp my engine (or indeed Minis with Oil Coolers) are likely to be running at.

I would not add a thermostat with an oil cooler. one more thing to go wrong. You have one on the radiator that does most of the cooling. If you did a lot of cold weather driving, you could think about one, or one that controls the air flow over it.

I wonder what they run in their free analysis? (quantity for motor oil analysis is 100 ml although you can get by with a few tests and 60 ml if nothing has to be repeated). This is one of those moments where my wife is right and I should have my oil analysis explications online in English. I do have a bunch of results, but all the reasons and details of what it tells is only on the Spanish site.
If you get it analyzed, post it and PM me so I see it and I'll comment. A good analysis should tell you not only whether it has kept it's viscosity, but kept it's additives and not oxidized. You can see a bunch of examples here: Oil analysis results and comments

As for how high temps can go, before I had the synthetics, I ran 25W-50 in most of the cars at the track. Ran one with Delo 15W-40 that had a transmission problem and ran full out in 3rd for his maximum speed, coupled by a driver who would not let him pass, filling the radiator with mud. The oil temp, measured at the filter was 155. Obviously it ran thin at that point, but the viscosity came back on cooling. The biggest mistake we made, as this was before I studied filters, was let him run with K&N. We ended up with 63 ppm of dirt in the oil. That was mostly responsible for the 62 ppm of iron. From the oil analysis it was impossible to tell how much damage there was to bearings from the thinning of the oil since we race with aviation gas that has lead in it. The analysis can't distinguish between bearing lead and lead additives. The 5 ppm of copper indicates that it didn't thin out too much (2ppm might have been normal).

Any good CI-4 motor oil will give you GL4 gear oil performance. It will be somewhere around 48 lbs on the Timken/Falex tester.

Why don't you try contacting them and see if they will disclose their zinc and phos levels? It is good to know the starting levels, as it tells you how much protection there is and lets you compare or calculate zddp additions. Also handy when comparing to used analysis to see how much is left. One of the reasons for the latest API category (SN) was the discovery that a lot of the cheaper phosphorus compounds used evaporated, reducing the protection and contaminating the catalytic converters.