Did an oil analysis on my Mazda

I did the Blackstone oil test after 5k and 18months or so - just the iron is a bit high - perhaps city driving. Viscosity is in the range. Oil was dark but they say color of oil is not an indicator.

I noticed significant engine braking on a freeway so I rushed and did the oil change. I do not know if it has anything to do with engine oil. Should I change at 1yr mark? Scotty tells that 5k or seals gets damaged.

Here is the results.

Those numbers look ok to me.

5k/1 year whichever comes first makes a lot of sense. Changing the oil and filter can only help, as long as done correctly.

I wonder why they don’t list the carbon content (the usual source for black oil), or the oil pH?

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Scotty Kilmer . . . ?! :roll_eyes:

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Simple-change it every year, forget Scotty. Nothing to do with engine braking.


I don’t know how anyone can understand what that guy says, he talks so fast. Just a lot of click bait titles.

You’ll get a lot of different answers here but I would never go 18 months. On my car that just sat, I changed once a year. I’d get 7-20 miles on it. On my Acura I change at 5000, and at 3000 on my Pontiac. The oil meter is somewhere around 40-50%. When you have north of $50,000 in rolling stock, worrying about an extra $50 a year for oil changes seems foolish. If I didn’t drive them as much I’d change at six months but never 18.

How do you know that 15 ppm of iron in the oil is detrimental to the engine? It might be more appropriate to look at the elements at the bottom of the list like molybdenum, calcium, boron, magnesium, phosphorus, and zinc. Except for magnesium, they are all lower than the universal average for those elements. That might indicate that the additives are lower than normal, if only a little low. That may mean your oil change interval is acceptable, or you might want to decrease it to one year and see how that affects the elemental analysis if you are conservative.

I will ask them on Monday.

Blackstone wants me to proceed with increasing it to 6k since the oil has not broken down!

Doing 5k on this car will take me to 1yr and 8monhts. BTW, Scotty didn’t limit the year but mileage.

Someone bought a 2017 Civic Turbo and changing oil at the dealer every 2yrs, and 20k miles - that is when the car’s computer alert him - apparently the car manual says change it every 1yr even if the car’s computer doesn’t alert. Putting these together make me to wonder whether I should go with 5k or 1.5yrs?

Just change the oil once per year. What could you possibly gain by putting it off longer?

On the other hand, it appears you drive this car 3000 miles per year. You could stop changing the oil altogether. Who cares if the engine blows up in 30,000 miles? That’s 10 years from now and the tires will be rotten by then, not to mention everything else rubber, brakes, etc.


I’m sorry, but you can’t expect us to take you seriously if you keep mentioning Scotty :roll_eyes:


Agree with that. Last I checked the cost for an analysis was around $30 which is about what it costs me to change my oil with Mobil 1. I did it once just for the heck of it but just don’t see the point in having more oil exams done. They sent me a bunch of mailers which are nice though.

The reason for not listing the carbon content, I’m guessing the answer is that they are probably using a mass spectrometer, which isn’t able to differentiate b/t elemental carbon (the source of the black color in used oil) and the carbon in the oil molecules.

Your vehicle does that? Mine will only do that if I manual downshift using the paddle shifter.

As far as oil&filter change that is up to you. As the old commercial says pay me now, or pay me later.

With your aversion to oil changes and low use, perhaps an electric, not a hybrid, would be a better choice.

Even if the spectrometer type cannot differentiate between the fundamental hydrocarbons forming the lubricant and resultant carbon soot from combustion blow-by, it can still be measured by comparative analysis. A clean sample of oil is analyzed and then compared to the “dirty” oil. Mass spectrometers (fixed magnetic sector, quadrupole etc), absorption spectrometers and time of flight spectrometers are all capable of quantitative measurement. Just subtract off the baseline and you have the concentration of particulate in the sample.

More likely, they are using absorption spectroscopy or an FTIR. It is far cheaper and easier to handle liquid analysis. Here’s a quick study for analyzing soot in a diesel engine oil sample:


Why didn’t they measure it? Perhaps it is because the soot will eventually result in wear. They are already looking for evidence of wear in the analysis of metals suspended in the oil. If there is no wear, who cares if there is soot below a level to produce wear from it? Then again, they did check for fuel dilution so who knows…maybe that is included in the Insolubles tally?

For pH level, I should have paid additional $10 and it is marked as “TBN”.
Carbon content is indicated in the measurement of “Insolubles”.

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I believe that you are doing it yourself.
I pay labor $30 (I used to pay $15) + parts
Lately keeping Walmarts Synthetic oil as a backup plan if Mobil is not on sale.

Pandemic gave me the wakeup call - with 3 cars, this car was idling - I just warmed it up once a month. Then one car got totaled - so this is now being used for local trips as well. Besides my Volt get changed every 2yrs as indicated by the car. So wondereed about going longer.

So if I have to go long trips, then I need to rent a car. My other car is Volt.
I use both for long trips. Volt is more comfy - feels like being in a Lexus with better gas mileage.

But EV batteries are consumable too - Volt batt lifetime is proportional to age than mileage. So does not make a financial sense.

This answered my question.
Blackstone recommended me to go to 6k instead since the oil did not breakdown - viscosity.
In any case, combined with Viscosity and additives, 18 months wasn’t bad - but perhaps the car drives a little better with the new engine oil. So 1yr to 18months does not seems to make a big difference - one caveat was perhaps the engine performance quickly dropped after the 1 yr mark - I need to make more observation. This might be when I should decide to change.

I got what to observe or look for - thanks all.
Appreciate your thoughts.

That’s all in your mind (like how some folks think their car drives better after getting it washed), or you have some other problem. Oil bad enough to cause any change in engine performance would throw HUGE red flags on a Blackstone analysis.

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Might be because drag is reduced - air flows smoothly after a wax!

My cars’ performance doesn’t change much just with a general wash up. But if I also clean all the windows spotless, inside & out, they seem to run a lot better! … lol