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Is Mono grade inherently more Oxidativly stable versus Mutli? I've been using Supertech API SG motor oil in the KTM last three years.
Mono-Grade Question
- Thread starter Fauxchemist2009
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No.
But SG has long been an outdated spec.
But SG has long been an outdated spec.
They can be. VII can also oxidize and thermally degrade:
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But the base stock is also important. PAO is more thermally stable than a Group III base stock, as is a Group III over a Group II and so forth. And high quality VII are more stable than lesser quality ones. It's why a fully formulated oil that has an approval that targets oxidation and sludge resistance is a more holistic approach.
When it comes to a monograde or a motorcycle oil being rated only API SG or similar, I not too sure anything can be read into this. I asked a similar question to oil formulator Weasley recently.
SR5: Weasley, you would know, why are some motorcycle oils the older API SG or SJ, even when a full synthetic and a non-ILSAC grade like 10W40 or 20W50. Yet others have a more modern API SL or SN?
Weasley: Quite frankly because until quite recently the newer API categories were simply not needed. Bikes tend to use higher viscosities and older ones have no catalyst. Most bikes use the same oil in the engine, gearbox and clutch so thin oils are not really wanted - plus bikes aren't under the same fuel economy or CO2 emissions regulatory pressures that cars have been, so no imperative to push the boundaries.
SR5: Weasley, you would know, why are some motorcycle oils the older API SG or SJ, even when a full synthetic and a non-ILSAC grade like 10W40 or 20W50. Yet others have a more modern API SL or SN?
Weasley: Quite frankly because until quite recently the newer API categories were simply not needed. Bikes tend to use higher viscosities and older ones have no catalyst. Most bikes use the same oil in the engine, gearbox and clutch so thin oils are not really wanted - plus bikes aren't under the same fuel economy or CO2 emissions regulatory pressures that cars have been, so no imperative to push the boundaries.
More monograde talk here
To me the thing to look for in a monograde is the Viscosity Index (VI), it should be over 100, and the higher it is the more certain you can be that you have a Group II monograde, which is what you want (or the very rare PAO monograde).
Then you want ZDDP (zinc) as an anti-wear & antioxidant agent. Plus a decent TBN (total base number) via a Ca / Mg detergent package, to neutralise acid buildup. Also dispersants to handle soot etc.
Right now I'm running a SAE30 monograde with a VI = 113 in my car. That VI means Group-II, so it's probably as oxidaivly stable as any other regular Group-II multigrades (like a regular 10W30), assuming they used a decent polymer VII (viscosity index improver) in the multigrade.
You original question may be referring to the bad old days of having a 10W40 made on a thin base oil then all jacked up on plastic VII, which sludged a lot of cars engines ages ago. Those days are over when they introduced minimum HTHS requirements for viscosity grades in J300.
To me the thing to look for in a monograde is the Viscosity Index (VI), it should be over 100, and the higher it is the more certain you can be that you have a Group II monograde, which is what you want (or the very rare PAO monograde).
Then you want ZDDP (zinc) as an anti-wear & antioxidant agent. Plus a decent TBN (total base number) via a Ca / Mg detergent package, to neutralise acid buildup. Also dispersants to handle soot etc.
Right now I'm running a SAE30 monograde with a VI = 113 in my car. That VI means Group-II, so it's probably as oxidaivly stable as any other regular Group-II multigrades (like a regular 10W30), assuming they used a decent polymer VII (viscosity index improver) in the multigrade.
You original question may be referring to the bad old days of having a 10W40 made on a thin base oil then all jacked up on plastic VII, which sludged a lot of cars engines ages ago. Those days are over when they introduced minimum HTHS requirements for viscosity grades in J300.
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