How do we define “severe service”?

When pushing our lubricants to their limits, we sometimes find the limits of the test equipment first.

Matt Erickson | TECHNICAL MANAGER – PCLT PRODUCTS AND MECHANICAL R&D

One of my responsibilities here at AMSOIL is to help develop tests in our mechanical lab designed to push lubricants to their limits, both ours and those of our competitors. An effective performance test accelerates lubricant degradation and forces the oil to its breaking point sooner than if tested in the field. This provides more data, faster.

The definition of “severe”

Given the severity of our testing, what happens when the equipment we test fails before our lubricants? Honestly, it causes us to simultaneously rejoice and curse. On one hand, we know our products withstand the toughest conditions we throw at them. On the other, we have to contend with the extra cost and hassle of test equipment that just isn’t built to handle the punishing conditions.

The August 2016 Tech Talk revealed how some two- and four-stroke equipment we’ve tested couldn’t stand up to our test conditions. We’ve run into the same predicament in the passenger car/light-truck market, too.

One recent incident involved the popular General Motors* 3.8L motor. Historically, the GM 3.8L is a rocksolid engine that’s powered millions of cars over the years. It’s a fixture in industry performance testing. One standardized test uses this engine under severe conditions for 100 hours. But our oils soldier through that test like a walk in the park, so we have to triple its length to 300 hours to get useful data. Not an easy task for equipment not designed to handle such extremes.

Well, we recently blew up a GM 3.8L engine. The image shows some of the carnage we found after removing the oil pan. All those bits and pieces used to be a piston.

We ran this test under extreme conditions, as if you were towing continuously at highway speeds uphill for weeks.

Unleaded gasoline

What happened, you ask? First, I’ll ease any concerns you might have: it wasn’t the oil’s fault. We were in uncharted territory, never having an oil last so long in this test before, so we knew we were on borrowed time. In fact, after more than four weeks of testing, the oil hadn’t even reached its breaking point. One of the exhaust valves broke off and fell into the cylinder, where it and the piston were pulverized into the mess you see here. As the piston and valve debris made its way to the oil pan, the crankshaft caught it and blew a hole in the side of the engine block. The severity of our test conditions combined with valve seat recession are to blame.

Years ago, lead was added to gasoline to, among other functions, lubricate the valve seats. Once lead was officially banned from gasoline, in 1996, the fuel no longer provided the same level of valve-seat protection. This lack of protection, combined with the extreme conditions of our test, invited valve recession. When valve seats recede, the valve no longer seats evenly. The result is a loss of heat-transfer that overheats and erodes the valve, as well as an uneven side load that causes the valve to bend slightly on every cycle. This onetwo punch eventually caused the valve to fail. We ran this test under extreme conditions, as if you were towing continuously at highway speeds uphill for weeks. Oil temperatures exceeded 300ºF. The extreme, 1,500ºF exhaust gas temperatures, combined with the constant stress of unevenly eroded valve seats, eventually led to valve failure, snapping a valve in half and destroying the engine.

But our oils soldier through that test like a walk in the park, so we have to triple its length to 300 hours to get useful data. Not an easy task for equipment not designed to handle such extremes.

Suitable for continued use

The good news, however, is the motor oil was still good. Even after hundreds of hours of operation so severe it destroyed the engine, the oil analysis still looked great. It made me smile to see our oil last that long, but it also made me cringe because we were going to have to once again re-test to try to get the oil to break.

This conundrum might present challenges to us engineers, but it amounts to you and your customers receiving the best synthetic lubricants available. We’re happy to keep blowing up engines in our mechanical lab to ensure your engines are protected out in the field.

Given the severe nature of our performance tests, the test equipment sometimes fails before our lubricants.

How to Test Engine Compression

John Baker|Mar 13, 2017 2:16 PM

Testing engine compression in the AMSOIL mechanical lab.

Engine compression = engine power.

A simple equation even we non-engineers can understand. Compression refers to the pressure your engine generates inside the cylinders while it’s running. How much pressure the engine produces and how well it converts that pressure into usable work influence your engine’s efficiency and power.

How it all works and how wear and deposits can erode compression (i.e. horsepower) over time are interesting topics you can read more about here. But today, we’re talking about how to test engine compression.

For this example, I used my 1998 Toyota Corolla. Don’t laugh. I paid cash for it and it runs as smooth as a sewing machine. I also sought the help of Pat Burgraff, one of the techs in our Mechanical Lab. Pat knows his way around an engine.

#1 Ensure the vehicle won’t start when you crank it over

Testing compression requires you to crank the engine several revolutions, and you don’t want it to fire in the process. Remove the fuel-pump and fuel-injection fuses so you’re not dumping gas into the cylinders each time you crank the engine. Then, disconnect the coil packs. Bear in mind the process for your vehicle may be different from the images here.

#2 Pull the spark plugs

Label the plug wires so you return them to the correct positions. Otherwise, your vehicle won’t start when you’re done. Thread the compression gauge into a spark plug opening. Take care not to cross-thread it. You can get a compression tester for less than $50 at most auto parts stores.

#3 Crank the engine

Have a helper crank the engine 5-10 times, or until the needle on the compression gauge stops ratcheting up. Note the psi and move to the next cylinder.

Thread the compression gauge into a spark-plug hole.

Crank the engine until the gauge stops ratcheting up.

What’s considered normal compression?

Here’s where things grow murky. “Good” compression depends on the engine. Unfortunately, engines don’t come with their proper compression stamped on the outside. But a good rule of thumb says that each cylinder in a mechanically sound engine should have compression of 130 psi or higher. While I’ve seen some people claim 100 psi is sufficient, the gearheads and other sources I’ve consulted consider that too low.

In addition, you want consistency from one reading to the next. Again, a good rule of thumb is no more than 10 percent variation between any of the cylinders. That’s not to say 15 or 20 percent variation in one cylinder means your engine is junk. But a good, healthy engine should demonstrate minimal variation.

My trusty Corolla nailed the test, making between 165-175 psi in each cylinder.

If one cylinder has low compression, try pouring about a teaspoon of oil into the spark-plug hole and retesting. If compression increases, it’s likely the rings are stuck or worn. The oil acts as a seal and helps close the gap between the rings and the cylinder wall through which the cylinder is losing pressure.

If that doesn’t work, it’s possible the valves or valve seals are worn.

If you suspect stuck rings, try an engine flush designed to clean deposits, such as AMSOIL Engine and Transmission Flush. You can also try a fuel additive that cleans pistons, like AMSOIL P.i.

Word to the wise: you may illuminate your check engine light performing this test, as I did. It went off by itself after driving a few miles, though.

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