Engine Oil Analysis 101 February 17 2017

We recently sent a sample of engine oil out to a lab to be analyzed to look for coolant in the oil as a symptom of a failing head gasket. The test came back negative for coolant, and we later found a tiny leak on an inaccessible side of the coolant reservoir. What we didn't expect was all the additional information we got about the health of our engine. Honestly, we regret not doing this earlier. Here is what we did and this is what you can gain from having your oil tested.

Disclaimer: We used Blackstone Laboratories, but are not affiliated with them nor are we receiving any consideration from them. 

- Service interval optimization: Engine oil loses its viscosity with use. As the viscosity decreases, the layer of oil in between the metal surfaces becomes thinner and thinner, until there is eventually metal-on-metal contact. On our BMW M3's, we change the engine oil about every 7,000 miles. This is shorter than what the BMW maintenance schedule and the dashboard service interval indicator recommends, so are we just wasting time and money with an unnecessarily short service interval? BMW has also stretched out their maintenance schedule after including free maintenance during the warranty period. If following BMW's service interval recommendations, is it causing premature wear, or is it acceptable? An oil analysis will measure the viscosity of the oil to see how much it has degraded and how much wear is occurring. The technician may also add notes and will often suggest a shorter or longer oil service interval based on your results.

- Early detection of other problems: The oil sample is also checked for traces of fuel and coolant. It is normal to have some fuel in the oil, but excessive amounts can point to issues with the fuel system and/or engine. Coolant in the oil can point to a failed headgasket or cracked block. Metal levels are also checked, and high levels of certain metals can point to excessive wear on particular components. Blackstone Laboratories has a chart that shows where each metal found in your oil may have come from.

- Dialing in the right viscosity: Sometimes the manufacturer will recommend different viscosities depending on your local climate conditions or driving conditions. Engine wear is a normal part of engine life, and tiny metal particles will be present in the engine oil. More metal particles means more wear. By experimenting with different viscosity oils and noting the corresponding wear, you can determine which viscosity oil is best for your engine. This is especially true for track cars, as the oil gets hotter than it would with street driving, and the manufacturer usually makes viscosity recommendations based on street driving.

We went to their website blackstone-labs.com and ordered a sample collection kit. They will send you one for free and charge you $28 when you send it back in for analysis.

Blackstone oil analysis kit components. Inner bottle, outer bottle, label, absorbent cloth, ziplock bag and form.

Here is everything taken out. The piece of cloth is an oil-absorbent material to catch any small leaks in-transit.

There are a couple of guidelines to get a good oil sample. Blackstone Laboratories recommends getting the engine oil up to full operating temperature before taking a sample. Also, when draining the oil from the oil pan, you want to take a sample from somewhere in the middle of the drain process. You don't want the first oil that comes out nor, the last oil that comes out. 

After taking your sample, package everything up, add postage and mail it off. It took several weeks from time of shipment for them to analyze our oil. We got back an email with the lab results and some notes. 

Sample report.

This is a sample report taken from the Blackstone Laboratories website. It is more interesting than ours, because it has data from multiple oil samples and shows how with regular testing, you can see trends and spikes for various metrics.

So next time you change your oil, you may consider sending in your oil for analysis. We certainly will be from now on.