Used Engine Oil Analysis

This article is about Used Engine Oil Analysis. The how to do it, where to send it, and what you can expect to learn are covered.

We’ve all heard the claims of extended oil drain intervals from the major oil manufactures. Some claim 10,000 miles, 15,000 miles, and one manufacturer claims their oil is good for one year or 25,000 miles.

Let’s find out how one of these oils has held up at the end of its recommended service life, and if it can be kept in service a while longer saving me the trouble and expense of an oil change. To do this I am going to take a small oil sample and send it out for analysis.

The oil under test is a national brand that advertises a one year or 25,000 mile service life. It has a viscosity of 5-20, and it has 15 months and 8000 miles of use in a 2013 Scion FR-S.

There are many firms that offer motor oil analysis. I have used a company called Oil Analyzers Inc. in the past to analyze used marine engine oil. I was pleased with their service so I chose them again for this article.

Oil Analyzers Inc. offers two levels of testing. I chose their Value Kit which test’s for viscosity, corrosion potential, wear metals, and beneficial oil additives. They also offer a comprehensive analysis kit which is designed to provide full test results which can be used for engine troubleshooting or establishing recurring drain intervals.

The Value Kit comes with instructions, a registration form, an oil container, and a mailer.

Before taking a sample of oil from the car, be sure to bring the engine up to operating temperature. This will ensure that any contaminates will be disbursed throughout the oil. If you are going to take a sample and change the oil at the same time it is recommended that you take your sample from the oil drain stream and not from the drain pan. If you intend to take a sample from the dipstick tube, don’t allow the siphon tube to rest on the oil pan bottom surface.

I chose to take a sample from the dipstick tube. I used ¼ inch clear tubing available at any hardware department, and a kitchen syringe for suction. I used the dipstick itself to measure the length of tubing I wanted in order to keep the siphon tube off of the bottom of the pan. Fish the siphon tube down the dipstick tube and place the syringe in the siphon tube. Then extract the oil and place it in the supplied container. There is a fill level marker on the container.

Now it’s time to fill out the paperwork. There are instructions and examples supplied. When you are ready ship the package to the address supplied. I choose the USPS. You can ship it using any carrier you wish. You can choose to have your results emailed, or sent to you by regular mail. There is also a website you can log onto to check your account and get your results. My results were emailed to me within a week of shipping.

Click here to view a PDF brochure from Oil Analyzers Inc. It describes the Oil Analysis program. Starting on page 8, take a look at the “Reading the Fluid Analysis Report” instructions. It shows exactly what your report will look like and it explains the test results.

The results from analyzing a 5-20 viscosity oil with 15 months and 8000 miles of use in a 2013 Scion FR-S are as follows:

  • Very low levels of wear metals were found to be present. Wear metals are described as the metal components within the engine.
  • A moderate level of the contaminant metal Silicon was present. Contaminate metals are described as dust and dirt. Silicon sources are listed asabrasives (dirt, Alumina Silica), seals and gasket material, lube additive or supplement, and/or environmental contaminants.
  • The level of the multi-source metal Boron was slightly low. Multi-source metals are described as additives.
  • The viscosity was found to be well within specification.
  • The TBN or Total Base Number, which is used to determine if the oil is becoming acidic, was within normal degradation limits.

The comments from the Analysis Report are: “Flagged data does not indicate an immediate need for maintenance action. Continue to observe the trend and monitor equipment and fluid conditions. Silicon is at a MODERATE LEVEL; SILICON sources can be abrasives (dirt, Alumina Silica), seals and gasket material, lube additive or lube supplement, and/or environmental contaminant; Boron is slightly low for this lubricant. Oil is suitable for continued use. Re-sample in 3,500 miles or 65 hours.”

I expected the oil to still be serviceable but I did not expect to see a high level of the metal contaminant Silicon, which is described in the report as dust and dirt. My course of action was to change the oil filter immediately. I had been using the stock Subaru filter but I changed it out for an Amsoil synthetic media filter. Look for a future article here on oil filter testing results. According to one report the three best oil filters tested were all synthetic media types.

My intent now is to run the oil for the recommended 3500 miles and change it. I will then have it tested again and I’ll compare both test results and report back to you here. At that time the oil will have around 12,000 miles and 21 months of service on it.

Picture of the Oil Analysis Kit contents



If you would like to have your oil analyzed you can purchase a kit from Oil Analyzers Inc. by clicking here.




I hope you have found this article about Used Engine Oil Analysis helpful.

Click here to read Used Engine Oil Analysis – Test 3. In Test 3 we analyze this oil again after it had accrued an additional 3500 miles of use. This was the recommended re-test service interval.

I value your comments, suggestions, and opinions. Please leave a comment below.

It’s all about the car!

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    2 Responses to Used Engine Oil Analysis

    1. Tom Peszek November 25, 2014 at 12:01 am #

      Very informative, I might look into doing an oil analysis on the Amsoil that I’m running in my Harley. I change it each year, but often wonder if I could run it longer since my mileage per year is pretty low.

      • Richard Horton November 25, 2014 at 10:04 pm #

        I’m glad you liked it Tom. Look for the next analysis coming soon.

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