Hey all,
Ok so i am a noob and proud of it. Recently I have spent hours searching the forum and google searching oil types and specs for my RX8 which has turned up some interesting results which i would like to share with you all and create a discussion for.
Engine oil is a big question asked many times on here which is good because it has gave me allot of pointers to go looking for further information regarding the subject.
Because the Rotary engine naturally burns oil in the cylinders it is no surprise that today's engine oil additives will coke up the apex seals but here is what i have found.
API codes, ACEA codes and ILSEC codes.
Reading through these standardised labels and specs as well as spending allot of time on the Castrol site has uncovered some interesting facts.
There are some new oils out with code specs C2, C3, C4.
These codes allow for very low ash as to protect the catalytic convertor. This is pretty useful for us as we can find a correct spec for the RX* seen as it suffers from this problem allot.
ACEA Engine Oil Specifications - oilspecifications.org
API standards
API Engine Oil Lubricant Specifications - oilspecifications.org
ILSAC standards
ILSAC Oil Specifications - oilspecifications.org
For the RX8 the minimum API spec is SL,SM so an API spec of SN is better. The key i have found is to find an oil with API spec greater than SL but also has at least a ACEA spec of C3 which has an ash, sulphated %wt of 0.8 or less so it burns clean.
A ACEA C4 burns even cleaner at around 0.4 %wt Ash but the API SL spec does not seem to be met with such low ash levels.
Furthermore Mineral and Semi-Synth oils have all had a massive load of additives added which makes their Ash, Sulphated values very high(~1.5%wt) and above so the Mazda manual recommending mineral oil is now out of date due to the additives.
That said there is some Castrol GTX with ACEA grade C4 but does not seem to meet the API SN spec again so one needs drop to a C3 standard to have the API SN grade again.
Both standards are met for conventional, semi-synth and synthetic EDGE titanium oils.
From what websites recommend they say A5/B5 grades which from the data sheets show a very high ash deposit when burnt so i not sure why they recommend this oil.
An API SN with ACEA C3 would be a minimum spec oil to today's standard for the rotary i would have thought.
In the UK we have the choice of 5W30 and upwards, i have not seen 5W20 on the shelf anywhere and i am convinced that a 5W30 from Castrol looses its lubricity in the rotary engine due to the heat it produces especially at 3000rpm and over.
API SN meets the ILSAC specs according to form so you cant use an oil without the container specifying this spec code. The addition of the C3 code seems the best option as they add less phosphor and sulphates in the oil so it burns cleaner from the way I understand it so it is a good choice to use it.
What do you all think, am I on the right track in selecting the best oil for my RX8 or have i just ventured down a rabbit hole into the dark depths of confused marketing jargon?
I am thinking of using Castrol EDGE Titanium 5W40 API SN with ACEA C3. Good or Bad choice?
And anyone know what we do about the 4 Litres of oil that does not drain from the oil coolers?
Ok so i am a noob and proud of it. Recently I have spent hours searching the forum and google searching oil types and specs for my RX8 which has turned up some interesting results which i would like to share with you all and create a discussion for.
Engine oil is a big question asked many times on here which is good because it has gave me allot of pointers to go looking for further information regarding the subject.
Because the Rotary engine naturally burns oil in the cylinders it is no surprise that today's engine oil additives will coke up the apex seals but here is what i have found.
API codes, ACEA codes and ILSEC codes.
Reading through these standardised labels and specs as well as spending allot of time on the Castrol site has uncovered some interesting facts.
There are some new oils out with code specs C2, C3, C4.
These codes allow for very low ash as to protect the catalytic convertor. This is pretty useful for us as we can find a correct spec for the RX* seen as it suffers from this problem allot.
ACEA Engine Oil Specifications - oilspecifications.org
API standards
API Engine Oil Lubricant Specifications - oilspecifications.org
ILSAC standards
ILSAC Oil Specifications - oilspecifications.org
For the RX8 the minimum API spec is SL,SM so an API spec of SN is better. The key i have found is to find an oil with API spec greater than SL but also has at least a ACEA spec of C3 which has an ash, sulphated %wt of 0.8 or less so it burns clean.
A ACEA C4 burns even cleaner at around 0.4 %wt Ash but the API SL spec does not seem to be met with such low ash levels.
Furthermore Mineral and Semi-Synth oils have all had a massive load of additives added which makes their Ash, Sulphated values very high(~1.5%wt) and above so the Mazda manual recommending mineral oil is now out of date due to the additives.
That said there is some Castrol GTX with ACEA grade C4 but does not seem to meet the API SN spec again so one needs drop to a C3 standard to have the API SN grade again.
Both standards are met for conventional, semi-synth and synthetic EDGE titanium oils.
From what websites recommend they say A5/B5 grades which from the data sheets show a very high ash deposit when burnt so i not sure why they recommend this oil.
An API SN with ACEA C3 would be a minimum spec oil to today's standard for the rotary i would have thought.
In the UK we have the choice of 5W30 and upwards, i have not seen 5W20 on the shelf anywhere and i am convinced that a 5W30 from Castrol looses its lubricity in the rotary engine due to the heat it produces especially at 3000rpm and over.
API SN meets the ILSAC specs according to form so you cant use an oil without the container specifying this spec code. The addition of the C3 code seems the best option as they add less phosphor and sulphates in the oil so it burns cleaner from the way I understand it so it is a good choice to use it.
What do you all think, am I on the right track in selecting the best oil for my RX8 or have i just ventured down a rabbit hole into the dark depths of confused marketing jargon?
I am thinking of using Castrol EDGE Titanium 5W40 API SN with ACEA C3. Good or Bad choice?
And anyone know what we do about the 4 Litres of oil that does not drain from the oil coolers?
New OILs for 2016 My findings and discussion
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