BY Jeff SmithImages by THE AUTHOR

t’s an exciting moment. You’ve just finished bolting that freshly built engine in your hot rod. The engine’s so new that you can smell the paint curing. You fire it up and take all the right steps to help that new engine run properly. After a few miles, you begin to think, “I hope I did everything right. How would I know if there’s a problem?” Those are the kind of thoughts that can cause sleepless nights for new engine builders.

Or, you’re considering the purchase of a nice muscle car from a car flipper. The seller has zero knowledge of the engine’s history, and while you’re suspicious of the engine’s background, it might be too good of a deal to pass up. In both cases there is a positive step you can take.

The answer is something called used oil analysis. It’s really a simple process that is not expensive and is as easy as capturing a sample of used oil and shipping it off for analysis. They say that knowledge is power, and this kind of used engine expertise could be invaluable. Think of it as cheap insurance.

There are several companies offering used oil analysis kits. We’ll be using two different ones from Oil Analyzers, which is the company that does the testing for AMSOIL and SPEEDiagnostix. There is also a service from a company called Blackstone that we’ve included for reference. All analysis companies offer a basic service where you request a packet that contains a sample bottle and return postage. You pull an oil sample from your warmed up engine and ship it off to them. Within a short period of time you will receive a full report of the test results.

Where the Numbers Come From

Wear metals indicate the amount of wear material in the oil sample. Low numbers in the single digits are what you want to see. Higher numbers can indicate a possible problem. Contaminant numbers should also be low. Excessive levels can indicate a problem that needs to be addressed.

Each company offers a similar service with varying options, but we’ll concentrate on the basic report and what all the different categories mean along with the testing company’s recommendations. We’ll also offer some suggestions for taking samples as well as other cool information you may find useful for monitoring your engine’s health and performance.

The introductory paragraphs mentioned both new and used engine evaluation and for most enthusiasts it can also be used to keep track of your current engine’s health. Once the sample is taken, the oil is shipped to a company like Oil Analyzers and after they receive the sample it only takes two to three days to compile a report that can then be quickly viewed online.

Once the evaluation is in your hands, you will be greeted with an array of results. The testing companies will make this process less complex by highlighting areas in the report that could be cause for concern. Typically, these highlighted areas will be green for normal levels, yellow for suspected minor problems, or red where there is cause for immediate action.

There are several layers of importance within a given engine’s used oil report card. Most used oil reports like the one from Oil Analyzers will break down the information into multiple areas but the two important categories are wear metals and contaminants. The wear metals should be easy to understand with iron, copper, tin, and aluminum as the most common. These are the ones that would demand close attention. Other information will offer what the Oil Analyzers test calls multi-source metals and additive metals.

Wear Metal Total and Contaminant Counts

We totaled up the wear metal and contaminants counts for all five of the engines tested. It’s clear that the 355ci TPI engine needs some attention because of contamination of the oil and high wear metal counts. Interestingly, the Silverado 5.3L engine with the highest mileage offered the lowest wear metals and contaminant counts.

The additive metals, as the name implies, are metals used in the additive package in the oil. Since different engine oils use different additive packages, it’s important that the original oil viscosity and brand information, like Valvoline 10W-30 for example, be included with the test report. The oil analysis companies know all the different additive packages and can use this information to more accurately access the condition of the used oil. As with any sample evaluation, the more accurate your information (and how you performed the test) the more accurately the company can offer its evaluation of the used oil sample.

The contaminants are listed as silicon, sodium, and potassium. Silicon is the big one as that material is directly related to dirt in the oil. This can come from many sources but is commonly the result of a poor-performing or non-existent air filter. The numbers used in all reports refer to these levels in parts per million (ppm). There will always be some dirt in the oil so levels in the single digits are considered normal, but you should also consider that some silicon is used in additive packages. This is why it’s important for the analysis company to know the brand and viscosity of the oil that they are testing.

One of the first tests we performed was on our 355ci small-block El Camino. We thought this would be a good engine to test because we had recently rebuilt the engine with fresh rings and bearings while retaining its flat tappet camshaft. It only took about three business days after mailing the sample to Oil Analyzers to get the results. What was surprising was the highlighted red numbers showing bearing wear with lead at 151 ppm and tin at 17 ppm. Both of these are high numbers.

We unfortunately gave some incorrect information on the oil used because we forgot that this was our only flat tappet camshaft engine, so we were using Comp’s high ZDDP oil to preserve the camshaft. We also failed to indicate that this was a freshly rebuilt engine. That was our fault. The test sample was also taken with the engine only partially warmed up after running it for less than a minute. This likely was the reason for the small amount of water in the oil. The oil was black so we’ve changed it and will put another 500 miles on the engine and test the oil again.

Parts List

This highlights the advantage of trend testing. This first test is representative of a new engine just establishing its wear patterns. We expect the numbers to come down substantially with a subsequent test. However, if the numbers remain high then this means we will need to disassemble the engine to determine the cause of the bearing wear numbers. This is a great illustration of how used oil analysis can be used to monitor the health of your engine and perhaps avoid a major problem.

Moving onto another test, we also looked at the used oil in a TPI fuel-injected 355ci engine in our V-8 swapped S-10 that had about 10,000 miles on the odometer. This engine has some miles on it, and we expected to see a normal wear metal count with no serious contaminants. We were wrong. The report came back with two warnings. One of moderately high iron and chromium wear metals that indicated higher-than-normal cylinder wall and ring wear. But the more serious admonition was the red flag levels of sodium as well as yellow warning levels of potassium in the oil indicating an internal coolant leak.

We noticed the last time we drove our S-10 that the coolant level was slightly low, but we assumed a minor external leak and merely topped it off with more coolant. The Oil Analyzers test revealed that we have a serious internal coolant leak that is probably a failed head gasket. So, our first step will be to change the oil and filter to flush the contaminants and then do some pressure testing to see if we can determine where the coolant is entering the engine. If we had not performed the oil analysis, the damage would have continued and eventually created a major failure.

We had also submitted a test for a daily driver ’07 Tahoe with a brand-new, rebuilt 5.3L LS engine. This engine had barely 100 miles on the clock at the time of testing. This analysis was performed by our friend Lake Speed Jr.’s SPEEDiagnostix company and also came back with some surprising results. Wear metals of copper and lead were at red flag levels but with a brand-new engine these numbers were not a surprise.

355ci TPI Engine

The Oil Analyzers report on this engine revealed that the sodium, potassium, and silicon levels point to an internal coolant leak that is entering the oil perhaps through a bad intake manifold gasket or head gasket. The sodium level is especially high and warranted a red warning as severe.

This coolant leak may also be contributing to higher wear metal numbers like the iron and chromium numbers that are higher than normal.

The report also showed a high level of silicon, but the evaluation stated that with new engines the silicon can also originate from new seals and gaskets. We did have to change the oil pan on this engine, and we added a new pan gasket using RTV in the corners so that is likely the reason for the higher-than-normal silicon numbers.

This test was from the initial break-in oil we used for the first 100 miles. These numbers would be serious if the engine had thousands more miles, but since this was from the break-in oil, we will need to run the engine for another 1,000 miles or so and test it again. Much like the high-wear metal numbers from our rebuilt 355ci small-block in our El Camino, we will need to do follow-up testing to establish a trend. Assuming the trend shows a significant downward curve (which we expect), then we will know the engine is OK. If not, then there might be some work ahead of us.

We sent in yet another sample to SPEEDiagnostix from an ’03 5.3L LS engine in a fullsize Silverado. This engine has 200,000 miles on the odometer and frankly we expected to see some wear metals on this engine given its rather aged condition. Again, we were mildly surprised to see this test result with a clean bill of health. All the wear metals reported in single digits and contaminants like water, glycol, silicon, or others were minimal. This engine has been the recipient of a dedicated oil change regimen over its entire lifespan and the oil analysis numbers reveal the fruits of those efforts. The hydraulic lifters clatter a bit for about 5 seconds when the engine is cold but otherwise this engine is as healthy as the SPEEDiagnostix numbers indicate.

While we started this story assuming that all of these tests would be somewhat boring as they’d all pass with good numbers. The surprise came when nearly every engine indicated some kind of minor problem with one that needed immediate attention. In this situation, it came down to the used oil tests showing us what we didn’t know. This has pushed us to pay closer attention to the oil sitting in the crankcase. Not all of our engines received a passing grade from these report cards. Armed with that knowledge, we now know what we need to do and all that came from a simple used oil test.

2. One vehicle we tested was a rebuilt 355ci small-block in our ’65 four-speed El Camino. The engine has around 800 miles on the new engine with a flat tappet camshaft and we were curious how it was performing. We expected the wear metals to be slightly high since it was a rebuilt engine.

4. A quality full synthetic can be counted on to always deliver better lubrication and better protection. Not all engines demand expensive full synthetics, but if you’ve spent significant money on a strong performance engine, quality oil is good insurance.

6. According to a Fram filter engineer we interviewed many years ago, he said, “the best oil filter in the world is a really good air filter.” These are words for your engine to live by and that also includes the PCV system. Street engines running without a PCV valve or without air filters are encouraging serious engine wear.

8. The red highlighted section in this test is from the 355ci carbureted small-block in our ’65 El Camino. The lead and tin numbers are excessive, which indicates excessive bearing wear. This engine was fresh from a rebuild with roughly 300 miles on the engine so it is possible these numbers will be lower with more miles. We’ve already changed the oil and will drive another 300 to 400 miles and re-test. If the lead and tin numbers are still high or climbing, then we will have to dismantle the engine to find the cause.

10. We also tested the TPI small-block in our S-10 that has been on the road for several rough years with 10,000 miles on the engine. We were surprised by sodium levels that were in the red danger zone and potassium levels were also high, indicating that antifreeze is entering the engine through possibly a bad gasket.