Oil questions

[Mustek]

Hi folks,

Is it ok to mix semi synthetic and mineral oil? They are both the same viscosity.

Do oils expire? One of them is 2-3 years old...

[pete-blen]

oil is cheap.... rebuilding a motor isn't...
Buy new oil & stop being a tight ass..

[MarkH]

Hi folks,

Is it ok to mix semi synthetic and mineral oil? They are both the same viscosity.

Do oils expire? One of them is 2-3 years old...

Oils don't expire, if exposed to air they will slowly absorb moisture though. A sealed container of oil that is 3 years old should be fine.

Yes, you can mix them, they wont explode.

Personally I wont use either of those oils though, not in my bikes.
I only use fully synthetic oil, the reasons are a bit complex - I read a ~70 page forum thread someone linked so as to be better informed on oil.
The highlights:
Fully synthetic oil maintains viscosity over a range of temperatures better than mineral oil, working better when cold and also when hot.
The important number is the 2nd one - 5w40 is bugger all different from 15w40, but 5w50 is 50 weight oil so is thicker and will cost some power/economy.
The first number (winter rating) is poorly defined, can't really trust an exact definition for it.
For motorcycles fully synthetic isn't more 'slippery' and wont make the wet clutch slip, but some additives will and therefore you need to avoid some car oils with friction reducing technology.

In my ST I'll only use fully synthetic because it only needs an oil change every 12,000kms and good oil is pretty cheap compared to >$12k for a 7 year old bike.
In my DR650 I'll only use fully synthetic because it is an air cooled bike so it experiences greater temperature variation than water cooled bikes do.
For any bike or car I've ever owned I can think of good reasons to use good oil, except maybe for one that was burning oil and would therefore get very expensive to by fully synthetic oil for.

[nzspokes]

Im using diesel oil in the Bandit. Seems to work just fine.

[MarkH]

Im using diesel oil in the Bandit. Seems to work just fine.

I'll use Mobil Delvac 1 5w40 if I can find it. It is fully synthetic oil that doesn't have the additives which bikes need to avoid, the picture of a truck on the bottle doesn't stop it from working well.

[Old Steve]

The first number (winter rating) is poorly defined, can't really trust an exact definition for it.
For motorcycles fully synthetic isn't more 'slippery' and wont make the wet clutch slip, but some additives will and therefore you need to avoid some car oils with friction reducing technology.

Quite a good summary MarkH, I'd just take exception with one comment. The first number, the W or Winter grade, is precisely defined under the SAE J300 Engine Oil viscosity specifications. The W grade addresses cold start and circulation properties, and as such the SAE specifies maximum dynamic viscosities at specific low temperatures for each W grade. There's definitely no guesswork about the specification of the SAE W grades.

And yes, a motorcycle engine oil which is also used in the transmission, should have a friction modifier for correct clutch operation. As such it should carry a JASO M classification showing it meets specific friction characteristics needed for motorbike operation. Those bikes which have separate gear box cases will use an automotive gear oil - this will have a classification under the API GL system.

And the belief that the higher the viscosity number the better the oil is not true. Internal engine clearances will determine the oil viscosity required. For instance, in my 17 year old Honda car with 150,000 km on the clock I use an SAE 5W-30, but of the highest performance classification possible. And if an oil is a synthetic (and that term is open for abuse) then that doesn't mean that it's a high performance oil. The oil additive package determines oil performance. I believe that the first Mobil 1 was not a very good oil, I think the Mobil engineers assumed that the synthetic basestock would contribute more to contamination control through it's superior oxidation resistance. They probably got it passed the performance tests required but I think that in service it wasn't such a superior oil and the additive package was upgraded not long after it's introduction. I do have, however, the highest regard for Mobil's modern synthetic oils, automotive and industrial. This from 25 years in the lubricant industry, a couple of years as the Technical Manager of one of the companies her in NZ and 9 years in that company's international technical centre.

[Kickaha]

This from 25 years in the lubricant industry, a couple of years as the Technical Manager of one of the companies her in NZ and 9 years in that company's international technical centre.

So really you wouldn't have a clue what you're talking about then :msn-wink:

[Katman]

And yes, a motorcycle engine oil which is also used in the transmission, should have a friction modifier for correct clutch operation.

I thought oil intended for wet clutch use should contain no friction modifiers.

[Flip]

5W50 describes the viscosity at two points on the viscosity/temp curve. Basically the oil behaves like a straight SAE 5 weight oil at 0 deg C and a 50 weight oil at 100 deg C. ie, its thinner when cold and thicker when hot compared to a straight 30 weight oil. Given most wear occurs at start up and a thinner oil circulates faster the bottom number is just as important as the upper one.

All oils are mixable unless you are using Castrol R race oil as a crank case lube as its vegetable oil based. Actually there is bugger all difference between semi and mineral based lube oils.

All the light disesl oils or mixed fleet lubes are very fine motor oils. I run them myself because they are full zinc and provide better lubrication protection than "modern" motor oils. Modern motor oils are designed to extend the life of catalitic converters and are light on certan important zinc based additives.

JASO have a test for motorcycle oils compatability with wet clutches, if the oil makers market them as bike oils they will have tested their oils against this standard. There is no SAE test for clutch compatability that I know of. If I had a bike that I suspected needed a clutch comptable oil I would look for one that has been tested to the JASO clutch compatability test. In my case imMobile1 V2 does and I use it for this reason.

I run a Valvolene 10W40 diesel oil in all my other vehicles; landy, BMW, Merc, MG, Austin and Suzuki 4WD, excpt for the HD that gets inMobile 1 V2 and the Lotus that gets imMobil 1 5W50.

But then WTF do I know!

[Flip]

I thought oil intended for wet clutch use should contain no friction modifiers.

They can have some just not too much. Those pesky Zinc addatives improve the lubricitity and are also detergents, some but not too much. Gear oil molibdumin EP addatives that used to be added to some motor oils 40 years ago are wet clutch killers.

[MarkH]

5W50 describes the viscosity at two points on the viscosity/temp curve. Basically the oil behaves like a straight SAE 5 weight oil at 0 deg C and a 50 weight oil at 100 deg C. ie, its thinner when cold and thicker when hot compared to a straight 30 weight oil. Given most wear occurs at start up and a thinner oil circulates faster the bottom number is just as important as the upper one.

I'm pretty sure that almost everything I've quoted here is very much wrong.
The 5W50 oil would vary LESS in its viscosity than say a 30w40 oil and I don't know that there is any oil that has unchanged viscosity through the temperature range.

From what I understand:
5w50 oil should be the viscosity of 50 weight oil at operating temperature.
If you took 5 weight oil and lowered the temperature until you reached a certain quite cold temperature, maybe it is -40°C but I'm not sure of the actual temperature, then at that temperature the 5w50 will flow as well as the thickened (due to the cold) 5 weight oil.
I'm sure there are technical documents that describe how to ascertain the w number, but it is NOTHING like you describe.

You don't really believe that a 0w40 oil has 0 weight viscosity at 0°C do you?

Also:
Maybe think about what you typed, you think that 5W50 will be 5 weight at 0° and 50 weight at 100°?
So you actually think that it is very thin when cold and thickens when it warms up?
Surely the more you think about it the more wrong that must seem?

I believe that the w number is more about extreme cold performance than anything else, if it gets really cold where you live than maybe a lower w number would be better.
However, good quality fully synthetic oils should flow quite well at cold temperatures and in NZ we shouldn't have a problem with any of the good oils.

[MarkH]

And the belief that the higher the viscosity number the better the oil is not true.

Wow, who believes that?
I won't touch 50 weight oil because my motorcycles' manufacturers specify 40 weight oil. Similarly I wouldn't use 30 weight in them either.
I'm aware that some Honda car engines are designed to run 30 weight oil and there is a new Mobil 1 that is 30 weight (0w30) so I'd use that if I had one of those cars.
There are also some newer Honda and Toyota engines that run on 0w20 - I wouldn't run 30, 40 or 50 weight oil in those.

My belief is that you should use the correct viscosity oil for your engine.

The w number might matter, but 15w, 10w, 5w and 0w are probably all fine where I live.
I can't really see that a pour point of -39°C or a pour point of -54°C would make a huge difference to me when I've never started my bike at a temperature under -5°C.

[Flip]

I'm pretty sure that almost everything I've quoted here is very much wrong.
The 5W50 oil would vary LESS in its viscosity than say a 30w40 oil and I don't know that there is any oil that has unchanged viscosity through the temperature range.

From what I understand:
5w50 oil should be the viscosity of 50 weight oil at operating temperature.
If you took 5 weight oil and lowered the temperature until you reached a certain quite cold temperature, maybe it is -40°C but I'm not sure of the actual temperature, then at that temperature the 5w50 will flow as well as the thickened (due to the cold) 5 weight oil.
I'm sure there are technical documents that describe how to ascertain the w number, but it is NOTHING like you describe.

You don't really believe that a 0w40 oil has 0 weight viscosity at 0°C do you?

Also:
Maybe think about what you typed, you think that 5W50 will be 5 weight at 0° and 50 weight at 100°?
So you actually think that it is very thin when cold and thickens when it warms up?
Surely the more you think about it the more wrong that must seem?

I believe that the w number is more about extreme cold performance than anything else, if it gets really cold where you live than maybe a lower w number would be better.
However, good quality fully synthetic oils should flow quite well at cold temperatures and in NZ we shouldn't have a problem with any of the good oils.

The 10W40 is a way to describe the viscosity curve of a motor oil by plotting two points on the temp/viscosity graph. Modern muitigrade oils have a flatter or better viscosity curve than old mono grade oils. The 10 number refers to the oils viscosity being the same as a straight 10 weight oil at low temp, the 40 is at high temp. Yes they use 0 and 100 because it is easy to calibrate in a lab.

So the viscosity curve of modern multigrade lubes are described at two temps as having in this case the viscosity of a straight 10 weight oil at low temp and the viscosity of a 40 straight weight oil at high temp. Compared to a mono grade oil they are thinner cold and thicker when hot. How else can you discribe complex viscosity curve without a complex equasion?

As a rule of thumb 0W30 oils for really cold enviroments and 20W60 for the desert. The 15W40's are all fine for NZ.

[bmws1r]

Synthetic oils have a high polymer shear strength, have a higher stable operating temp, and tend to keep the rated viscosity for more heat cycles.

However they also flow twice as fast as the equilivent mineral oil, ie older design engines with bigger designed clearances it is not suited in some designs.

I used the shell advance range of motorcycle oils, until they stopped selling them here in NZ, no problem I'll just use shell rotella, but then they changed the formula, not suitable for motorcycles anymore.

[Voltaire]

Synthetic oils have a high polymer shear strength, have a higher stable operating temp, and tend to keep the rated viscosity for more heat cycles.

However they also flow twice as fast as the equilivent mineral oil, ie older design engines with bigger designed clearances are not suited.

I used the shell advance range of motorcycle oils, until they stopped selling them here in NZ, no problem I'll just use shell rotella, but then they changed the formula, not suitable for motorcycles anymore.

I gather that synthetic does not break down as quickly as Dino oil.
I've been running Penrite Full Synthetic extra Zinc in my 1972 BMW Racer and it gets run to 8000 RPM, seems to go ok and still on original mains.
but that's a plain bearing engine, don't know about ball or roller main motors.

[MarkH]

Compared to a mono grade oil they are thinner cold and thicker when hot.

Yeah, sorta, but you get that they are not actually thinner cold and thicker hot, don't you?
They are thinner as they get hotter and thicker the colder they are, just not as much as older types of oil like 30w40.

I do wonder what mono grade oil is exactly. An oil without a w rating would still be more viscous when colder and less viscous when hotter.

[MarkH]

As a rule of thumb 0W30 oils for really cold enviroments and 20W60 for the desert. The 15W40's are all fine for NZ.

This is also something to be careful of.
In cold environments and in the desert the fully warmed operating temperature of the engine is the same (controlled by thermostat). So using a 30 weight oil or a 60 weight oil in the same engine would be a bad idea. In colder climates using a 5w40 oil may be better than using a 15w40 oil due to the lower pour point, but either is a 40 weight oil at operating temperature. 20w60 oil should only be used for engines designed to run with 60 weight oil. 0w30 oil should only be used for engines designed to run with 30 weight oil.

[Kickaha]

20w60 oil should only be used for engines designed to run with 60 weight oil. 0w30 oil should only be used for engines designed to run with 30 weight oil.

I bought some Penrite Mineral HPR 20W60 today, it will be used in an engine which originally specified 30W and now most people run 20W50 in them

On the Oil container it says " may be used where a 20W50 or 30W oil is recommended"

[pritch]

I thought oil intended for wet clutch use should contain no friction modifiers.

Me too.

My advice to the OP would be to try and find out what oil the manufacturer recommends and use that. RTFM?

Internet oil threads can become quite ummm exciting? :corn:

[Flip]

Yeah, sorta, but you get that they are not actually thinner cold and thicker hot, don't you?
They are thinner as they get hotter and thicker the colder they are, just not as much as older types of oil like 30w40.

I do wonder what mono grade oil is exactly. An oil without a w rating would still be more viscous when colder and less viscous when hotter.

A mono grade oil is a old school oil with out any Viscosity Index additives (V.I.). Pre 60's oil technology.

Multigrade grade oils are thinner when cold and thicker when hot. Thats what multi grade oils are. Thats what the V.I. additive does. A say 20W40 oil is the same viscosity cold as a 20 weight oil and the same viscosity as a 40 weight oil hot. Its as simple as that.

One interesting thing is a 20w40 oil is blended from 20 weight base stock. The V.I. additive is like gorilla snot (it actually looks like a head cold) the additive is not very shear stable and breaks down with shear/work (espcially gear boxes). Thats why oils thin with use. Thats also why your bike always changes nicer with new oil. Thats also why bikes change their oil sooner than cars, they are harder on oils. Synethic oils have less VI addatives (some none) so provide better more stable life espcially in bikes.

[Old Steve]

Actually the SAE W grade and the straight grade are not two points on a viscosity curve. They are two totally different measurements. The W grade is a measurement of dynamic viscosity, that is the viscosity of the oil while it is not moving, at a low temperature so it reflects the oil's performance at start up and how the viscosity of the cold oil affects cold cranking - the W grade is measured in centipoise at different temperatures, the SAE 15W is measured at -15 deg C (I can always remember that one), SAE 10W is measured at -20 deg C, SAE 5W at -25 deg C etc. There is also a cold cranking test where the oil has to have a cold cranking viscosity less than a stipulated target at a much lower temperature for each W grade. The straight SAE grade measures kinematic viscosity, the viscosity of the oil when moving, measured in centiStokes. Each grade has a range of viscosities which the oil must be between to meet that grade, viscosity is measured at 100 deg C for all grades. The straight grade must also meet certain shear stability targets set at a higher temperature and under shear conditions to simulate the oil's shear stability in the ring belt area.

Wet clutch motorcycle engine oil does contain friction modifiers, they allow us to slip our clutches (along with the cooling effect of the clutch being surrounded by oil and the lubricity effect of the oil as well) and there are specific tests that the oil must meet to be classified JASO friction modified (used to be JASO MA, but I think there are later classifications now).

Zinc is an anti-wear additive, it also has anti-oxidant properties. It comes in the form of primary or secondary, zinc di alkyl (or di aryl) thiophosphate, it's a sulphur phosphorus compound. Zinc has no detergent properties. Detergents are organic bases which are also used to neutralise acid by-products of combustion or oxidation. Zinc does have a slight effect on catalysts, so latest PCMOs (passenger car motor oils) are starting to use non-zinc organic anti-wear additives similar to those used in locomotive engine oils for a long time.

Detergents are mainly based on calcium or magnesium organic compounds and their function is to remove contamination particles from engine surfaces. An engine oil will also contain organic dispersants which surround contaminant particles and hold them in suspension in the oil, these dispersant additives also provide a slight detergent function in that they will strip contaminant particles from the engine wall to a certain extent, but not to the extent that the detergent will.

And multigrade engine oils don't get thinner at low temperatures and thicker at higher temperatures, no oil can. What they do is that they thicken less as temperature drops, and thin out less as temperatures rise. For most motor vehicles in New Zealand, an SAE 15W-40 is usually a good viscosity grade choice. But certain vehicles have specific viscosity requirements for our ambient temperature ranges which are specified by the manufacturer.

Then there's the performance classification of the oil, but we won't go into that here.

[MarkH]

Multigrade grade oils are thinner when cold and thicker when hot. Thats what multi grade oils are. Thats what the V.I. additive does. A say 20W40 oil is the same viscosity cold as a 20 weight oil and the same viscosity as a 40 weight oil hot. Its as simple as that.

And yet on the technical information from Mobil the viscosity at 40° is thicker than at 100°.
Some of the stuff you posted is more or less correct, then other stuff like quoted here - not so much.

Just think about 0w30, if it was the same viscosity cold as 0 weight oil then it would not be able to protect an engine, logically this just can't be the case.
It seems that Old Steve has a better understanding of oils, I certainly don't know enough to pull him up on anything he has said.

[varminter]

FFS, Fontera's in trouble, use butter.

[Mustek]

oil is cheap.... rebuilding a motor isn't...
Buy new oil & stop being a tight ass..
Lol. Point taken