Why is flashpoint a concern?
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Patman
Staff member
Someone correct me if I'm wrong, but a lower flashpoint generally means the oil will evaporate
more easily, as some parts of the engine can turn the oil a lot hotter than an oil temp gauge
would suggest. So from what I understand, a low flashpoint can mean the oil will oxidize
faster than an oil with a higher flashpoint.
more easily, as some parts of the engine can turn the oil a lot hotter than an oil temp gauge
would suggest. So from what I understand, a low flashpoint can mean the oil will oxidize
faster than an oil with a higher flashpoint.
Yes. You don't want your oil to burn off into the air. You want it to stay in the engine, and so you get the highest flash point possible.
Flashpoint and evaporation rate are not directly relate, although they do correlate in some instances. The hotter you get an oil will cause some parts of it to evaporate but by comparing the flashpoints of oils you will not be able to accurately determine what types will evaporate quicker. A low flashpoint will mean that a substance will burn at a lower temperature, when talking oils though, oxidation is not a result of burning in its common sence it is a result of an oxygen molecule being bonded at a week spot on the molecule of oil. Flashpoint is generally used for shipping purposes and for testing for fuel dilution in an engine.
A Low flash point will cause oxidation, sludge, oil thickening....
Kind of like this:
Kind of like this:
I think you have to look at flashpoint and NOACK to get some feel for how an oil will evaporate. You also have to look at the temps the oil will reach.
My car's oil temps stay in the 200-230 range, so I'm not too concerned about flashpoint. If you have an air-cooled engine, or an engine that keeps high oil temps, flashpoint would be of a much greater importance.
My car's oil temps stay in the 200-230 range, so I'm not too concerned about flashpoint. If you have an air-cooled engine, or an engine that keeps high oil temps, flashpoint would be of a much greater importance.
MS, I agree with Joel 100%. What you are showing is an oil that may have over extended it's ability to go a certain amount of miles and due to the oils ability to resist oxidation over a period of time can cause that as well. This is not due to a low flash point. I know schaeffers oils flashpoint isn't the lowest but not the highest either, does that make it a poor canidate for an oil. No, not even close.
There is many oils with much lower flashpoints and if standard oil drain procedures(depending on oil drain intervals) are followed, you wont find what you are showing in your picture. This is why many lube centers just recommend a 3k oil drain as this is the safest limits without over taxing any oil. It is when you start extending oil drains past the 3k that a lower quality oil will start to push its limits.
So point is, Flashpoint is just one instrument to help determine just how high the base oil can go but as discussed earlier, it does not in no way prove that the oil is inferior/superiour to any other oil. Engine oils DO NOT see those kind of temps for any period of time that would cause this burn off if the oil's additive package is doing it's job.
This is not to say that flashpoint issue
is not important, particularly when looking at extending oil drains, but there is some companies that use this in marketing and to an uneducated consumer, would seem to make sense but by marketing an oil with flashpoint being the main issue is NOT the end all to end all of a making of a good oil and should not be the main reason for choosing such.
There is many oils with much lower flashpoints and if standard oil drain procedures(depending on oil drain intervals) are followed, you wont find what you are showing in your picture. This is why many lube centers just recommend a 3k oil drain as this is the safest limits without over taxing any oil. It is when you start extending oil drains past the 3k that a lower quality oil will start to push its limits.
So point is, Flashpoint is just one instrument to help determine just how high the base oil can go but as discussed earlier, it does not in no way prove that the oil is inferior/superiour to any other oil. Engine oils DO NOT see those kind of temps for any period of time that would cause this burn off if the oil's additive package is doing it's job.
This is not to say that flashpoint issue
is not important, particularly when looking at extending oil drains, but there is some companies that use this in marketing and to an uneducated consumer, would seem to make sense but by marketing an oil with flashpoint being the main issue is NOT the end all to end all of a making of a good oil and should not be the main reason for choosing such.
MolaKule
Staff member
From a previous post:
1. If Mobil has a flash point of 392, isn't that almost dangerously low?
The Flash Point is the point at above which the "vapors" of the fluid would be ignited with an "open" flame. In other words, you have to get the lubricant hot enough to make it evaporate, and then only if there is "high" concentration of vapors, it might ignite at this temperature. Again, it only refers to the vapors of the fluid, not the liquid itself.
In my view, some people make too much of flash point. I consider volatility a better meaure of the oil's capability at high temps. The volatility (Noack - D5800) test is an attempt to correlate oil evaporation (vapor creation) with engine performance. I say "attempt" because the test temps are much higher than one would see in normal operation.
The only time I worry about flashpoint is in refractory situations where the oil's vapors might come into contact with hot surfaces, such as a in a steel mill or in a brick making factory.
1. If Mobil has a flash point of 392, isn't that almost dangerously low?
The Flash Point is the point at above which the "vapors" of the fluid would be ignited with an "open" flame. In other words, you have to get the lubricant hot enough to make it evaporate, and then only if there is "high" concentration of vapors, it might ignite at this temperature. Again, it only refers to the vapors of the fluid, not the liquid itself.
In my view, some people make too much of flash point. I consider volatility a better meaure of the oil's capability at high temps. The volatility (Noack - D5800) test is an attempt to correlate oil evaporation (vapor creation) with engine performance. I say "attempt" because the test temps are much higher than one would see in normal operation.
The only time I worry about flashpoint is in refractory situations where the oil's vapors might come into contact with hot surfaces, such as a in a steel mill or in a brick making factory.
MolaKule
Staff member
Sorry Ken, have to disagree. You are talking about autoignition, not flash point.
The definition I gave comes from McNeil's book on Tribology.
The definition I gave comes from McNeil's book on Tribology.
oops your right,
I guess I was talking about volitility.
**** I love this board. There is a bit of a correlation between vaporation and flashpoint, Molakule has the perfect definition in his post, in that vaporation is a component that goes into flashpoint but not vice versa. Compare oil to water, the oil has a much lower flashpoint, but the water will have a much higher evaporation rate.
MolaKule
Staff member
Good analogy, Joel.
MSPARKS:
That picture you posted earlier on this thread came from Toyota Sienna - the infamous sludger engine.
I haven't the foggiest idea what the previous owner did for oil changes as I bought it used. The picture was a result of me getting a "before/after" scenario established prior to me using the Auto-rx product from Frank Miller. I just wanted to establish a baseline prior to any work being done.
That picture you posted earlier on this thread came from Toyota Sienna - the infamous sludger engine.
I haven't the foggiest idea what the previous owner did for oil changes as I bought it used. The picture was a result of me getting a "before/after" scenario established prior to me using the Auto-rx product from Frank Miller. I just wanted to establish a baseline prior to any work being done.
Man, I feel for you, that is 1 reason I don't buy used vehicles, though in your case with the (engine design) I dont think it would matter.
Hope the engine is better now.
Engine runs great but MPG sucks....
Tried several things:
Put new twin tips plugs in (owners manual calls for twin tip, all I could find where the premium Boschs. $24 for 6 of those bad boys).
Used a bottle of Lucas UCL. didn't really see much of an improvement there, either.
We'll keep waiting to see what happens.....
Tried several things:
Put new twin tips plugs in (owners manual calls for twin tip, all I could find where the premium Boschs. $24 for 6 of those bad boys).
Used a bottle of Lucas UCL. didn't really see much of an improvement there, either.
We'll keep waiting to see what happens.....
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