So, I have a 1974 Mini with original engine... which engine oil should I be using? My mechanic is sticking semi-synthetic in, but there are minieral oils out there for engines pre-1980.
My Mini burns oil quite nicely! LOL - and wonder, therefore, if the semi-synthetic is too thin?
Comments please :grin:
Engine Oil
Started by
ianbunyan
, Oct 08 2005 02:20 PM
9 replies to this topic
#2
Jammy
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Moved Into The Garage
Posted 08 October 2005 - 05:23 PM
Use mineral oil, either 15/40 or 20/50. Synthetic oils contain chemicals that kinda eat the engine slowly, and while modern engines are able to withstand this, older engines can't. If you do a search for synthetic oil you'll probably get a more detailed explanation.
#3
ianbunyan
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Mini Mad
Posted 08 October 2005 - 11:28 PM
Thanks for that 
How do I tell my mechanic of many years that he is wrong though?? HMMmmm... maybe if I ring Bill Richards then I can tell my mechanic a specialist told me... not that I am saying you're not a specialist, of course 
Thanks!
How do I tell my mechanic of many years that he is wrong though?? HMMmmm... maybe if I ring Bill Richards then I can tell my mechanic a specialist told me... not that I am saying you're not a specialist, of course Thanks!
#4
ianbunyan
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Mini Mad
Posted 08 October 2005 - 11:40 PM
Oooh, I found this at: http://www.minimaste.../mini-oils.html
The short version for my 1974 Mini is: Use Millers Classic Transverse 'M' 20W-50 Mineral oil specially formulated for "gearbox in sump" engines.
--8<--------------- FULL ARTICLE ------------------------
Mini Lubrication (Part 1) - Engine Oils (updated Feb 04)
The A-Series engine is unique in that it shares the same oil used for both the transmission and the engine. This gives the oil designers a difficult dilemma: to compromise between the needs of the transmission (less heat, more load) or the engine (higher heat, more viscocity, emission clean).
Although details of oil composition and features of oil adsorbtion, viscocity, and other friction characteristics would be too much for this article (and the subject of many texts), some basic rules do exist that help to understand the oil ratings such as SAE rating (also known as the viscocity index). At a particular temperature, the higher the rating, the more viscous the oil is or using a more common expression:
The higher the SAE number, the thicker it is.
Oil gets thinner as it gets warmer. However, an oil needs to be chosen so that it can lubricate when the engine is first started (i.e. it is at the same temperature as the outside air), and when it is warm. Often, it can take a good ten minutes before the oil is warmed up properly. This can take even longer in the gearbox and transmission.
In Summer, use thicker oils (i.e. higher SAE number). In Winter, use thinner oils.
Historically, oil used to be selected according to the season. Oils with higher SAE rating (viscocity) would be used in the summer than in the winter. This was so that when the engine is cold, the oil would not be too thick. Unnecessarily thick oil can lead to huge amounts of drag, and poor circulation. It can put tremendous pressure on oil pumps and seals as oil struggles to move around the many small feed pipes. In some cases (including one of our own customers), gear selection in winter can be almost impossible because the oil in the engine/gearbox is too thick.
Thicker oils (SAE 30+) suit older mini engines better.
On the other hand, too thin an oil can lead to lubrication problems and engine wear at high engine power/speed, and in places where larger gaps exist (i.e in transmission, main bearings and pistons seals). It can also escape through gaps such as old-style seals and worn bores. This in turn, can contaminate the fuel mixture as it does not burn as easily as petrol, thus increasing emissions of hydrocarbons. Therefore, for older mini engines, too thin an oil will result in heavy oil usage, potentially higher engine wear and likely failure of emission tests.
Newer mini engines based on the A+ engine are stated as being built with much higher accuracy and lower tolerances, thus reducing oil use enormously. The seals on modern engines are also much more efficient. Therefore, much thinner oils can be used, which in turn reduces drag (when cold) and improves economy.
However, there have been cases reported where thinner oils (generally fully synthetic oils) even in later mini engines have caused symptoms like low oil pressure and transmission problems. So err on the side of caution, and stick with slightly thicker oils for general use (at least 20W40 or 20W50). NOTE however that the workshop manuals for the A+ state 10W30 or 10W40. So take your pick!
The same oil in summer will be much thicker in winter.
The trick therefore is to get oil that has the right viscocity in summer and winter. An option is to use different oils at different seasons (which is recommended for older mini engines). The other option is to use multigrade oils. These have a double rating, with the first rating the equivalent viscocity in winter, and the second in summer. An example in 20W40 (the W stands for Winter). Here the viscocity is equivalent to oils of SAE 20 used in winter and SAE 40 in summer.
This multi-grade specification can seem confusing. It doesn't mean that the oil is thinner in winter than in the summer. In fact, the trick is to almost read it in reverse: read the smaller number as how thin the oil can get, and the larger number of how thick it can get.
Then apply a general rule of thumb: use thicker oils for older or high-mileage (worn) engines; use thinner oils for more modern engines or high-performance applications.
To illustrate, the following multi-grade specs are listed together with their typical use:
10W60 is for old/classic engines that need to perform when hot.
10W30 is for modern engines that need to perform when hot.
20W60 is for old/classic engines that are run normally.
40W60 is for really old engines that used to run on Castor Oil.
Many modern oils use additives to control the viscocity and improve the "cleanliness" of the engine. Some have additives to improve the cling of the oil to the metal and its load handling (excessive load on thin hot oil can cause it to break down).
Fully synthetic oils offer a great variety of performance in cold and warm conditions, and can sustain better loads at hotter temperatures. Oils with a minimum SAE of 15 or less are often fully or semi synthetic. However, they are very expensive compared to mineral oils. A good compromise for most ordinary use is a semi-synthetic oil.
Good, clean lubrication is important for engine maintenance: select a good oil and change it regularly.
--------------------------------------------------------------------------------
So, which oil to use?
There are two factors to consider:
Is the engine an old-style engine or one that is worn?
if so, choose a higher summer SAE (SAE 60), else choose a lower summer SAE (SAE 40).
Is the engine being used for sport/performance use?
if so, choose a lower winter SAE (semi/fully synthetic SAE 10), else choose a higher winter SAE (SAE 20-30).
There are two main manufacturers of specialist oils for older engines, where thicker oils for summer and winter are developed. These are Penrite and Millers. Both companies have also developed specialised multigrade oils for older engines, and engines that have the gearbox and engine utilising the same oil feed.
For owners of older minis or minis with high-mileage engines, a slightly thicker oil is recommended (in the SAE 20-50 range) for standard use. Examples include Millers Transverse M (rated 20W50) and Penrite Classic 20W50. However, we recommend you don't go for too thick an oil as this can cause more wear and drag when cold.
If using your mini for sport but you have an older engine, then thinner semi-synthetic or even fully synthetic oils (SAE 10-30) may be more preferable to reduce drag in order to optimise performance and horse-power, but not too thin to escape and burn. Examples include Millers XSS (semi-synthetic) 15W50 or Penrite HPR (semi synthetic) 15W60
For more modern minis, or minis with high performance or newer/higher-quality engines, a thinner oil for reduced drag and better economy is suggested. Examples include Millers XSS (semi-synthetic) 10W-40 or Penrite Classic Synthetic 10W50.
The marketing for oil can be misleading, as "Classic" oils are those for classic or older style engines, but the rating needs to be chosen for use and condition of the engine. "Sport" or "High Performance" oils usually indicate semi-synthetic or fully synthetic for high-performance and high load. However, the SAE viscocity rating still needs to be selected for use and condition of engine. Fully synthetic oil selected too thin for classic race engines may result in "high consumption" or high oil loss.
--------------------------------------------------------------------------------
Relevant Millers Oils
Those highlighted are recommended by Minimaster.
Name SAE Rating Description
Classic: Special semi-synth & mineral oils for classic cars
Classic 20W-50 All mineral oil for cost-effective use in older-style, high mileage engines.
Classic Sport 20W-50 Semi-synthetic oil for older-style, high-mileage engines.
Classic Transverse 'M' 20W-50 Mineral oil specially formulated for "gearbox in sump" engines.
Classic Transverse 'M' Sport 20W-50 Semi-synthetic oil specially formulated for "gearbox in sump" engines.
XFS: High Performance synthetic oils for classic cars
XFS 10W-60 10W-60 Fully synthetic high-performance oils for older style engines used for classic racing and rallying.
XFS 15W-50 15W-50 For older or high-mileage race engines.
XFS 10W-40 10W-40 For newer, more modern or low mileage race engines.
--------------------------------------------------------------------------------
Name SAE Rating Description
XFS: Modern High Performance Synthetic Oils
XFS 5W-30 5W-30 Fully synthetic high-performance oils for modern economy engines.
XFS 5W-40 5W-40 Fully synthetic high-performance oils for modern performance engines.
XFS 10W-40 10W-40 Fully synthetic high-performance oils for highly-stressed performance engines.
CFS: Competition Fully Synthetic Oils
CFS 5W-40 5W-40 Fully synthetic high-performance competition oil with improved additives for high loads, high film strength, outstanding cold flow properties. Ideal for small high revving engines.
CFS 10W-40 10W-40 As per CFS 5W-40, but better for slightly higher mileage smaller capacity engines up to 1500cc.
CFS 10W-60 10W-60 As per CFS 5W-40, but better for larger capacity engines, e.g. 2000cc and above. Ideal for V8 engines.
CFS 15W-60 15W-60 As per CFS 5W-40, but better for larger capacity engines and high endurance racing or rallying.
CSS: Competition Semi-Synthetic Oils
CSS 10W-40 10W-40 Semi synthetic competition oil for high performance applications where fully synthetic ultimate performance is not required.
CSS 20W-50 20W-50 Semi synthetic competition oil specially formulated to be SAE50 for better oil pressure under high-performance conditions. Ideal for larger classic competition engines such as Jaguar, Healey, MG, TR etc.
Specialised Competition & Performance Oils
CTV 20W-50 20W-50 Semi synthetic competition oil specially formulated for transverse engines with oil in sump gearboxes, but with flow rates equivalent to about SAE15. Ideal for competition mini use.
CPS 20W-50 20W-50 Semi synthetic competition oil with high-performance characteristics for competition use, but cost effective compromise of mineral oil and semi-synthetic formula.
CB40 SAE40 40W Castor Oil with enhanced anti-oxidant for enhanced performance. Designed for cars running on Methanol or alcohol-based fuels such as the Judd EV-V8 hill climb car.
CRO30 10W40 10W40 Test bed running in oil for competition engines with quality solvent-refined mineral oils, for high protection of highly stressed components whilst providing suitable boundary lubrication allowing good bedding in of pistons. Suitable for 5-hour test bed running.
--------------------------------------------------------------------------------
Relevant Penrite Oils
Those highlighted are recommended by Minimaster.
Name SAE Rating Description
Classic 20W50 20W50 Specially formulated mineral oil, designed for vehicles from the 1960s and 70s. Hard-wearing, full-bodied oil with excellent film strength under heavy loads.
Classic Synthetic 10W50 Fully synthetic for high-performance modern classics such as the Mazda, MGF etc.
HPR Range: High Performance Semi Synthetic
HPR 15W/60 15W60 Semi synthetic for multi-cam, multi-valve performance engines offering good all-round performance from good pumpability when cold to good viscocity when hot.
HPR 20W/60 20W60 Replacing the SAE30 and 20W50 multigrade, this semi synthetic oil is ideal for high performance post war classics such as MGs, Porsches and Minis.
HPR 40 25W60 Replacing the SAE40, this multigrade semi synthetic oil is ideal for most engines from the 1920s and 30s with a special additive pack to improve hot oil pressure and oil consumption.
Shelsey Range: High Performance Mineral Oils
Shelsey 15W60
20W60
25W60 Oils designed for older engines that haven't been overhauled or run on a non-detergent oil. Designed with special non-dispersants, The Shelley oils will reduce the possibilty or removing deposits from pistons and rings thereby reducing compression, increasing oil consumption, and flushing contaminants into the lubrication system.
The short version for my 1974 Mini is: Use Millers Classic Transverse 'M' 20W-50 Mineral oil specially formulated for "gearbox in sump" engines.
--8<--------------- FULL ARTICLE ------------------------
Mini Lubrication (Part 1) - Engine Oils (updated Feb 04)
The A-Series engine is unique in that it shares the same oil used for both the transmission and the engine. This gives the oil designers a difficult dilemma: to compromise between the needs of the transmission (less heat, more load) or the engine (higher heat, more viscocity, emission clean).
Although details of oil composition and features of oil adsorbtion, viscocity, and other friction characteristics would be too much for this article (and the subject of many texts), some basic rules do exist that help to understand the oil ratings such as SAE rating (also known as the viscocity index). At a particular temperature, the higher the rating, the more viscous the oil is or using a more common expression:
The higher the SAE number, the thicker it is.
Oil gets thinner as it gets warmer. However, an oil needs to be chosen so that it can lubricate when the engine is first started (i.e. it is at the same temperature as the outside air), and when it is warm. Often, it can take a good ten minutes before the oil is warmed up properly. This can take even longer in the gearbox and transmission.
In Summer, use thicker oils (i.e. higher SAE number). In Winter, use thinner oils.
Historically, oil used to be selected according to the season. Oils with higher SAE rating (viscocity) would be used in the summer than in the winter. This was so that when the engine is cold, the oil would not be too thick. Unnecessarily thick oil can lead to huge amounts of drag, and poor circulation. It can put tremendous pressure on oil pumps and seals as oil struggles to move around the many small feed pipes. In some cases (including one of our own customers), gear selection in winter can be almost impossible because the oil in the engine/gearbox is too thick.
Thicker oils (SAE 30+) suit older mini engines better.
On the other hand, too thin an oil can lead to lubrication problems and engine wear at high engine power/speed, and in places where larger gaps exist (i.e in transmission, main bearings and pistons seals). It can also escape through gaps such as old-style seals and worn bores. This in turn, can contaminate the fuel mixture as it does not burn as easily as petrol, thus increasing emissions of hydrocarbons. Therefore, for older mini engines, too thin an oil will result in heavy oil usage, potentially higher engine wear and likely failure of emission tests.
Newer mini engines based on the A+ engine are stated as being built with much higher accuracy and lower tolerances, thus reducing oil use enormously. The seals on modern engines are also much more efficient. Therefore, much thinner oils can be used, which in turn reduces drag (when cold) and improves economy.
However, there have been cases reported where thinner oils (generally fully synthetic oils) even in later mini engines have caused symptoms like low oil pressure and transmission problems. So err on the side of caution, and stick with slightly thicker oils for general use (at least 20W40 or 20W50). NOTE however that the workshop manuals for the A+ state 10W30 or 10W40. So take your pick!
The same oil in summer will be much thicker in winter.
The trick therefore is to get oil that has the right viscocity in summer and winter. An option is to use different oils at different seasons (which is recommended for older mini engines). The other option is to use multigrade oils. These have a double rating, with the first rating the equivalent viscocity in winter, and the second in summer. An example in 20W40 (the W stands for Winter). Here the viscocity is equivalent to oils of SAE 20 used in winter and SAE 40 in summer.
This multi-grade specification can seem confusing. It doesn't mean that the oil is thinner in winter than in the summer. In fact, the trick is to almost read it in reverse: read the smaller number as how thin the oil can get, and the larger number of how thick it can get.
Then apply a general rule of thumb: use thicker oils for older or high-mileage (worn) engines; use thinner oils for more modern engines or high-performance applications.
To illustrate, the following multi-grade specs are listed together with their typical use:
10W60 is for old/classic engines that need to perform when hot.
10W30 is for modern engines that need to perform when hot.
20W60 is for old/classic engines that are run normally.
40W60 is for really old engines that used to run on Castor Oil.
Many modern oils use additives to control the viscocity and improve the "cleanliness" of the engine. Some have additives to improve the cling of the oil to the metal and its load handling (excessive load on thin hot oil can cause it to break down).
Fully synthetic oils offer a great variety of performance in cold and warm conditions, and can sustain better loads at hotter temperatures. Oils with a minimum SAE of 15 or less are often fully or semi synthetic. However, they are very expensive compared to mineral oils. A good compromise for most ordinary use is a semi-synthetic oil.
Good, clean lubrication is important for engine maintenance: select a good oil and change it regularly.
--------------------------------------------------------------------------------
So, which oil to use?
There are two factors to consider:
Is the engine an old-style engine or one that is worn?
if so, choose a higher summer SAE (SAE 60), else choose a lower summer SAE (SAE 40).
Is the engine being used for sport/performance use?
if so, choose a lower winter SAE (semi/fully synthetic SAE 10), else choose a higher winter SAE (SAE 20-30).
There are two main manufacturers of specialist oils for older engines, where thicker oils for summer and winter are developed. These are Penrite and Millers. Both companies have also developed specialised multigrade oils for older engines, and engines that have the gearbox and engine utilising the same oil feed.
For owners of older minis or minis with high-mileage engines, a slightly thicker oil is recommended (in the SAE 20-50 range) for standard use. Examples include Millers Transverse M (rated 20W50) and Penrite Classic 20W50. However, we recommend you don't go for too thick an oil as this can cause more wear and drag when cold.
If using your mini for sport but you have an older engine, then thinner semi-synthetic or even fully synthetic oils (SAE 10-30) may be more preferable to reduce drag in order to optimise performance and horse-power, but not too thin to escape and burn. Examples include Millers XSS (semi-synthetic) 15W50 or Penrite HPR (semi synthetic) 15W60
For more modern minis, or minis with high performance or newer/higher-quality engines, a thinner oil for reduced drag and better economy is suggested. Examples include Millers XSS (semi-synthetic) 10W-40 or Penrite Classic Synthetic 10W50.
The marketing for oil can be misleading, as "Classic" oils are those for classic or older style engines, but the rating needs to be chosen for use and condition of the engine. "Sport" or "High Performance" oils usually indicate semi-synthetic or fully synthetic for high-performance and high load. However, the SAE viscocity rating still needs to be selected for use and condition of engine. Fully synthetic oil selected too thin for classic race engines may result in "high consumption" or high oil loss.
--------------------------------------------------------------------------------
Relevant Millers Oils
Those highlighted are recommended by Minimaster.
Name SAE Rating Description
Classic: Special semi-synth & mineral oils for classic cars
Classic 20W-50 All mineral oil for cost-effective use in older-style, high mileage engines.
Classic Sport 20W-50 Semi-synthetic oil for older-style, high-mileage engines.
Classic Transverse 'M' 20W-50 Mineral oil specially formulated for "gearbox in sump" engines.
Classic Transverse 'M' Sport 20W-50 Semi-synthetic oil specially formulated for "gearbox in sump" engines.
XFS: High Performance synthetic oils for classic cars
XFS 10W-60 10W-60 Fully synthetic high-performance oils for older style engines used for classic racing and rallying.
XFS 15W-50 15W-50 For older or high-mileage race engines.
XFS 10W-40 10W-40 For newer, more modern or low mileage race engines.
--------------------------------------------------------------------------------
Name SAE Rating Description
XFS: Modern High Performance Synthetic Oils
XFS 5W-30 5W-30 Fully synthetic high-performance oils for modern economy engines.
XFS 5W-40 5W-40 Fully synthetic high-performance oils for modern performance engines.
XFS 10W-40 10W-40 Fully synthetic high-performance oils for highly-stressed performance engines.
CFS: Competition Fully Synthetic Oils
CFS 5W-40 5W-40 Fully synthetic high-performance competition oil with improved additives for high loads, high film strength, outstanding cold flow properties. Ideal for small high revving engines.
CFS 10W-40 10W-40 As per CFS 5W-40, but better for slightly higher mileage smaller capacity engines up to 1500cc.
CFS 10W-60 10W-60 As per CFS 5W-40, but better for larger capacity engines, e.g. 2000cc and above. Ideal for V8 engines.
CFS 15W-60 15W-60 As per CFS 5W-40, but better for larger capacity engines and high endurance racing or rallying.
CSS: Competition Semi-Synthetic Oils
CSS 10W-40 10W-40 Semi synthetic competition oil for high performance applications where fully synthetic ultimate performance is not required.
CSS 20W-50 20W-50 Semi synthetic competition oil specially formulated to be SAE50 for better oil pressure under high-performance conditions. Ideal for larger classic competition engines such as Jaguar, Healey, MG, TR etc.
Specialised Competition & Performance Oils
CTV 20W-50 20W-50 Semi synthetic competition oil specially formulated for transverse engines with oil in sump gearboxes, but with flow rates equivalent to about SAE15. Ideal for competition mini use.
CPS 20W-50 20W-50 Semi synthetic competition oil with high-performance characteristics for competition use, but cost effective compromise of mineral oil and semi-synthetic formula.
CB40 SAE40 40W Castor Oil with enhanced anti-oxidant for enhanced performance. Designed for cars running on Methanol or alcohol-based fuels such as the Judd EV-V8 hill climb car.
CRO30 10W40 10W40 Test bed running in oil for competition engines with quality solvent-refined mineral oils, for high protection of highly stressed components whilst providing suitable boundary lubrication allowing good bedding in of pistons. Suitable for 5-hour test bed running.
--------------------------------------------------------------------------------
Relevant Penrite Oils
Those highlighted are recommended by Minimaster.
Name SAE Rating Description
Classic 20W50 20W50 Specially formulated mineral oil, designed for vehicles from the 1960s and 70s. Hard-wearing, full-bodied oil with excellent film strength under heavy loads.
Classic Synthetic 10W50 Fully synthetic for high-performance modern classics such as the Mazda, MGF etc.
HPR Range: High Performance Semi Synthetic
HPR 15W/60 15W60 Semi synthetic for multi-cam, multi-valve performance engines offering good all-round performance from good pumpability when cold to good viscocity when hot.
HPR 20W/60 20W60 Replacing the SAE30 and 20W50 multigrade, this semi synthetic oil is ideal for high performance post war classics such as MGs, Porsches and Minis.
HPR 40 25W60 Replacing the SAE40, this multigrade semi synthetic oil is ideal for most engines from the 1920s and 30s with a special additive pack to improve hot oil pressure and oil consumption.
Shelsey Range: High Performance Mineral Oils
Shelsey 15W60
20W60
25W60 Oils designed for older engines that haven't been overhauled or run on a non-detergent oil. Designed with special non-dispersants, The Shelley oils will reduce the possibilty or removing deposits from pistons and rings thereby reducing compression, increasing oil consumption, and flushing contaminants into the lubrication system.
#5
Robbie224
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- Noobies
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- 20 posts
Learner Driver
- Location: Portsmouth
Posted 03 June 2022 - 06:50 PM
Excellent oil info. A series engine completely rebuilt everything renewed should be OK with XFS 10W-60 fully synthetic oil ?
#6
Cooperman
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- TMF+ Member
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- 23,039 posts
Uncle Cooperman, Voted Mr TMF 2011
- Location: Cambs.
- Local Club: MCR, HAMOC, Chelmsford M.C.
Posted 03 June 2022 - 07:57 PM
A quality 20w50 oil is what virtually everyone uses in classic Minis so long as it has a high ZDDP (zinc) level of 1200 ppm or greater.
The exception is with automatics which seem to like a 10w40.
Valvoline VR1 is excellent.
The exception is with automatics which seem to like a 10w40.
Valvoline VR1 is excellent.
#7
Hpal
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- Noobies
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- 96 posts
Stage One Kit Fitted
- Location: Hunter Valley
Posted 03 June 2022 - 09:46 PM
Excellent oil info. A series engine completely rebuilt everything renewed should be OK with XFS 10W-60 fully synthetic oil ?
I would say no, do not use synthetic oil in a mini.
Penrite HPR30 (20w60) is a very good choice.
#8
Robbie224
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- Noobies
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- 20 posts
Learner Driver
- Location: Portsmouth
Posted 04 June 2022 - 04:50 AM
Thank you for repies. Very much appreciated
#9
Tones61
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- Members
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- 424 posts
Speeding Along Now
- Location: Plymouth
Posted 04 June 2022 - 05:31 PM
VR1 20/50 valvoline
#10
hazpalmer14
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Super Mini Mad
- Local Club: cumbria mini cruisers
Posted 04 June 2022 - 08:33 PM
Millers 20w50 CTV
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