If you’re looking to determine what your best oil change intervals should be, the best method is via oil analysis. Of course, on small vehicles which require only 4 or 5 quarts of oil, the cost of the oil analysis is nearly as much as a complete oil change.

Of course, the end result is that most folks won’t ante up for a professional oil analysis. However, they might be willing to perform their own “oil analysis”, if they knew how to do it. Of course, such an analysis won’t give you readings as accurate and precise as results from a lab, but it can give you a pretty decent understanding of how well your oil is holding up.

In the next few paragraphs you’ll find detailed instructions for one of six DIY oil analysis tests that you can use to establish the condition of your oil and whether it’s ready for a change.

You might also want to consider learning a bit more regarding oils and filters in general. You might find the following sites useful in this quest.

- No More Oil Changes – Everything you need to know about oil, but didn’t know to ask

- The Motor Oil Evaluator –

- A Motor Oil Forum for discussion of motor oils

The Business Card Test

Putting this simple test into practice can reveal a plethora of potential oil problems that might necessitate draining of the oil: build-up of condensation, contamination with anti-freeze, high particulate levels, dispersant additive deterioration, fuel in your oil, products of oxidation and sludge build-up.

You should place a drop of used oil on the surface of chromatography paper (good heavy white card stock works pretty well too) – make sure the engine/oil is WARM (not HOT). Place your white paper/card someplace where it will be suspended parallel to the ground and so that the oil drop area will be touching nothing – on either side of the card. For instance, if you’re using stiff card stock or a stiff business card (which you really should be) you could set the card across the top of a coffee cup.

You want to be patient and wait for the paper or card to absorb the oil drop completely which might take awhile. Once all of the oil has been drawn into the pores of the paper you should be able to begin evaluating the condition of your oil.

- A colorless circle or somewhat yellowish outer ring = “good” oil.

- A dense, dark deposit zone = Dispersant additive failure

- A black, pasty area = Anti-freeze in your engine oil

- Center of circle dark with distinct outside ring = Severe oxidation

- A dark center with surrounding rings = Fuel in oil, Fuel dilution

Information for this test featured in: Fitch, J.C., “The Lubrication Field Test and Inspection Guide”, Noria Corporation 2000

The article shown below will describe for you one from a total of six incredibly useful oil analysis tests you can use to quickly establish the continued viability of your oil, without ever paying a single dime to an oil analysis lab.

The crackle test is valuable for establishing whether water build-up from condensation is an issue. Typically, you will be most susceptible to water build-up in your oil if you are a short trip driver and/or if your vehicle sits for long periods without being run.

Why a water test? Because water doesn’t lubricate very well and because water build-up leads to acid build-up. Acid causes corrosion , and that can lead to pitting. Of course, you don’t want pitting in your engine. Even a high TBN extended drain synthetic oil like AMSOIL can eventually be overcome by water/acid build-up. So, as a general rule, you’d probably want to know if you were getting water in your oil BEFORE acid build-up depletes the acid fighting additives in your oil. For this reason, I recommend performing the crackle test.

However, if using the blotter spot test prior to the crackle test shows that you have fuel in your engine oil, performing the crackle test will likely give inconclusive results, since the fuel in your oil will “throw off” your results. This is the reason that the blotter spot test (business card test) is most often performed PRIOR TO the crackle test. If you’ve got fuel in your oil, you may already need to change out your oil, and the results of the crackle test will not be clear anyway.

The test goes something like this: place a small amount of oil onto a hotplate of some type (just a few drops is plenty). You want to set the hotplate to a temp greater than 212 degrees F (the boiling point of water). Since motor oil won’t typically be volatile till 350 degrees F or higher, setting the temp of the hotplate anywhere between 250 and 300 should work well.

Listen for the sound of the crackle. At 300+ degrees, you should soon hear the crackle of the boiling water, that is IF you’ve got water in your motor oil. The more oil you place on the plate, the longer it will take the water to boil, so keep the amount to a minimum.

A professional oil analysis will be more accurate in that it will tell you if the level of water in the oil is a problem and what the level is, but the the DIY crackle test detailed here is a good, cheap way to establish water ingression.

The best way to establish realistic oil change intervals is via oil analysis. The problem is, a complete oil analysis can easily run you about as much as a 5 quart oil change – with petroleum oil anyway.

So, for many motorists, the better option is to perform a “Poor Man’s Oil Analysis”. It is not likely to give you results as accurate and precise as the ones you’d get from a lab, but you will get a pretty decent notion of just how effectively your engine oil is holding up.

In the next few paragraphs you will discover the complete details for performing one of six DIY oil analysis tests which can be used to establish the condition of your oil and whether it’s ready for a change.

You might also want to consider learning a bit more regarding lubricants and filters in general. Quite alot of information can be gleaned from the following sites.

- No More Oil Changes – tons of motor oil information

- The Motor Oil Evaluator – motor oil comparison specifications

- A Motor Oil Forum for discussion of motor oils

The Business Card Test

This test reveals oxidation products, sludge formation, dispersancy failure, glycol contamination, water contamination, fuel dilution, and high levels of particles.

You want to place a drop of used oil on the surface of chromatography paper (good heavy white card stock works pretty well too) – make sure the engine/oil is WARM (not HOT). Place your white paper/card suspended horizontally above a table or countertop and so that the oil drop area will be touching nothing – on either side of the card. For instance, if you’re using stiff card stock or a stiff business card (which you really should be) you could lay two pencils down on a table (parallel to each other) and set the card with each end sitting on one of the pencils.

Make sure that the oil spot is entirely dry before trying to evaluate the appearance of the oil drop. At the point where the paper/card has completely drawn all the oils into itself it is then time to begin evaluating the condition of your oil.

- A colorless circle or slight yellowish outer ring = “good” oil.

- A dense, dark deposit zone = Dispersant additive failure

- A black, pasty area = Anti-freeze in your motor oil

- Center of circle dark with distinct outer ring = Severe oxidation

- Center of circle dark with outer rings = Fuel in oil,Fuel dilution

Information for this test featured in: Fitch, J.C., “The Lubrication Field Test and Inspection Guide”, Noria Corporation 2000

It is best to rely on oil analysis to determine your oil change interval. Of course, on many passenger car vehicles that only take 4-6 quarts of motor oil, the price of the oil analysis can be nearly as much as a complete oil change.

So, for some, the best thing is to execute a “Poor Man’s Oil Analysis”. It is not likely to provide information as accurate and precise as those derived from an oil analysis lab, but it can give you a pretty decent notion of just how effectively your engine oil is handling the extremes within your engine.

In the next few paragraphs you’ll find detailed instructions for one of six DIY oil analysis tests that you can use to establish the condition of your oil and whether it’s ready for a change.

You might also want to consider learning a bit more about oils and filters in general. You might find the following sites useful in this quest.

- The Motor Oil Bible – tons of motor oil information

- The Motor Oil Evaluator – motor oil comparison specifications

- A Motor Oil Forum for discussion of motor oils

The Spot Test

Putting this simple test into practice can unveil a plethora of possible oil degredation issues that might lead to the necessity for draining of the oil: build-up of condensation, contamination with anti-freeze, high particulate levels, dispersant additive deterioration, fuel in your oil, products of oxidation and sludge build-up.

You want to place a drop of used oil on the surface of chromatography paper (good heavy white card stock works pretty well too) – make sure the engine/oil is WARM (not HOT). Place your white paper/card suspended horizontally above a table or countertop and so that the oil drop area will be touching nothing – on either side of the card. For instance, if you’re using stiff card stock or a stiff business card (which you really should be) you could lay two pencils down on a table (parallel to each other) and set the card with each end sitting on one of the pencils.

Wait until the oil drop is no longer moist. Use the list below to evaluate the condition of your oil based on the DRY oil spot.

- A colorless circle or slight yellowish outer ring = “good” oil.

- A dense, dark deposit zone = Dispersant additive failure

- A black, pasty area = Anti-freeze in your motor oil

- Center of circle dark with distinct outside ring = Severe oxidation

- A dark center with surrounding rings = Fuel in oil, Fuel dilution

Information for this test featured in: Fitch, J.C., “The Lubrication Field Test and Inspection Guide”, Noria Corporation 2000