Oil Choice
#1
Posted 26 January 2022 - 07:21 AM
#2
Posted 26 January 2022 - 12:10 PM
While browsing through a Haynes manual (#646 with light blue cover) Chapter 14 supplement, I read where the oil recommendation has been changed from 20w/50 to 10w/40. Curious to know the benefit of the change.
I've found it's best to stick to a good quality 20w/50, due to the gearbox sharing the same oil.
#3
Posted 26 January 2022 - 12:11 PM
It was to do with the CAT.
#4
Posted 26 January 2022 - 03:35 PM
As nick said,also to do with emissions and catalyst
Edited by Tones61, 26 January 2022 - 03:36 PM.
#5
Posted 26 January 2022 - 05:50 PM
10w/40 was also the recommendation for cold climates. I used to sell Castrolite 10w/40 to winter customers back in 60's/70's.
#6
Posted 26 January 2022 - 06:30 PM
No one clued up uses 10/40 in a manual a series.
#7
Posted 27 January 2022 - 02:06 AM
Nothing to do with emissions, it was rover standardising oil across the range.
No one clued up uses 10/40 in a manual a series.
OK then. Good to know that I’m clued up as I’ve been using 20/50 for years. Was Castro GTX but like Valvoline VR-1 better.
#8
Posted 27 January 2022 - 04:42 AM
The later Mk1 manual says 10W/30 or 10W/40 above -18C (with a note that 20W/50 or 20W/40 may be used above -12C ambient)
You need the oil to be thin enough when cold to enable near-instant oil feed to the rockers & camshaft and thick enough hot to give good oil pressure. Plus in a mini keep care of the gearbox
#9
Posted 27 January 2022 - 07:12 AM
Edited by croc7, 27 January 2022 - 07:15 AM.
#10
Posted 27 January 2022 - 08:06 AM
#11
Posted 27 January 2022 - 02:39 PM
Edited by cal844, 27 January 2022 - 02:40 PM.
#12
Posted 27 January 2022 - 11:01 PM
What could be the problem using 20W50 with a catalyser?
#13
Posted 28 January 2022 - 01:06 AM
There is no issue with 20w50 and catalytic converters. Any oil related concerns with catalytic converters deal with the oil specification ratings - specifically, the amount of zinc or zinc-based compounds in the oil.
More modern (mid 2000's on) oil ratings specify lower levels of zinc to avoid poisoning the catalytic material. Any 20w50 oil with a modern rating will be perfectly safe with a catalytic converter.
As to the necessity of 20w50 for Minis, I disagree with most other opinions. The oil viscosity index has little relation to the lubricating properties or the shear strength of the oil molecules. It primarily deals with how the oil flows when cold and its properties when hot. The "50" means it acts like a 50 "viscosity" oil when hot.
With older vintage oils, where the oil molecules are less stable and prone to shearing and decomposition, this could be important in hot conditions. With modern oils, especially synthetics, the molecular chains are much stronger (synthetic molecules are engineered stronger and don't need as many perishable additives to gain multi-viscosity properties.)
For a non-synthetic oil, I would guess that any real problems with 10w40 was related to the wider viscosity spread. Natural oil is single viscosity by nature.
As I wrote, additives are needed to give conventional oil multi-viscosity properties. The wide the spread, the more additive ("VI improver") needed, and this breaks down faster under duress. Perhaps the 10w40 broke down more rapidly than owners expected, I don't know.
But I'd want to see proof of that, like records of Rover's warranty claims, vs. anecdotal testimony. If these problems were that bad there should be evidence from warranty returns, since the then-new injection Minis would have come with 10w-40 as factory fill and likely be dealer-serviced for at least the warranty period if not longer using the same oil. Enough failures ought to have resulted in a class-action lawsuit against Rover.
Dave
#14
Posted 28 January 2022 - 03:32 AM
https://penriteoil.c.../brands/classic
Enjoy.
#15
Posted 28 January 2022 - 01:06 PM
viscosity aside, the other factor that needs to be taken into account with
There is no issue with 20w50 and catalytic converters. Any oil related concerns with catalytic converters deal with the oil specification ratings - specifically, the amount of zinc or zinc-based compounds in the oil.
More modern (mid 2000's on) oil ratings specify lower levels of zinc to avoid poisoning the catalytic material. Any 20w50 oil with a modern rating will be perfectly safe with a catalytic converter.
on this point, it's my understanding that the manual gearbox needs an oil with decent amounts of zinc etc compounds to avoid excessive wear on the synchro assemblies, so this as well as viscosity should be taken into account when choosing an oil
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