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How to tackle oil consumption issues

Sunday, April 1, 2018 - 06:00
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Have you noticed lately that some of your customers’ engine oil levels are low even though the mileage interval has not been met? Well, you’re not alone, since many OEs have been using thinner viscosity oil for their new engine designs to meet the CAFÉ (Corporate Average Fuel Economy) standards. 

Before we go to deep into this subject, we need an understanding of the oil that is required in today’s modern engine. For years, we looked at an oil bottle only taking notice of the name brand and oil weight to maybe decide on whether to use it in the engine we are working on. Those days are over, my friend, now there are recommendations called service ratings that classify passenger and commercial vehicle motor oils by the American Petroleum Institute (API). Your most likely familiar with the API donut (Figure 1) that is on every oil bottle that has the two letter rating of the oil. The letters that you need to look for currently are either SM or SN, and supersedes the previous ratings. The donut also has the Society of Automotive Engineers (SAE) viscosity grade that have the common numbers on the bottle such as 0W-20 or 5W-30 and so on. 

Figure 1

By the way, the “W” after the first number does not stand for weight but rather for a “winter” designed oil. A 5-30 is not the same as a 5W-30 oil so be careful to use the specific recommended oil. Manufacturer requirements and specifications are listed in all the popular service information systems.  

Another important thing to remember is the difference between gasoline and diesel engine requirements. The specification for the engines are different, and it is vital that the correct oil be used. Rather than the SN rated oil, diesel engines require the use of a CJ-4 oil. The C stands for commercial engines (diesel engines) and J is the current performance level while the 4 in a J-4 oil indicates a 4-stroke diesel engine. Believe it or not, there is still more to understand before we move on to some problem vehicles. The OE’s require the correct oil, and in some cases the oil filter, to be installed in the engine before they will even think about running their oil consumption test. More on the test later in the article but for now let’s move on with a few more bits of important information. There are another bunch of letters that are on the oil bottle such as ILSAC (International Lubricant Standardization and Approval Committee) that is common on oils that are used in Asian vehicles, such as GF-5 that is now recommended. The next standard, ACEA (Association des Constructeurs Européens d'Automobiles), that is a specification that must be used if you are changing oil on any European engine. The ACEA is a performance/quality classification such as A3/A5 tests that are used in Europe. This standard for European engines is more stringent than the API and ILSAC standards. Be aware if there is an engine issue due to lubrication, the OE will take an oil sample and send it to a lab for testing. When the lab results comes back, it must indicate the correct viscosity along with the approved rated oil for the engine was used or no warranty bucks will be paid out. Don’t be left on the hook for an expensive engine repair job due to improper oil usage. It’s always better to purchase a good quality oil that has the correct specifications to prevent damage to today’s very expensive engines.

Consumption causes

There are many issues with oil consumption on today’s engine whether it’s a leak due to poor engine breathing or sealing. Consumption can also be caused by poor engine design such as piston ring, piston or engine block design issues. Since the engines we are working on are not our father’s Oldsmobile design, the amount of oil usage is different than years ago. The amount of normal oil usage has drastically changed in the past five to ten years. For many years, the normal amount of oil consumption was considered to be a quart of oil every 3,000 to 4,000 miles after completing the engine break-in period. 

Figure 2

This is not the case today as you can see by the ODIS VW factory scan tool screen shot (Figure 2) that states that up to 0.5 quart of oil in 600 miles is normal on VWs built from 2000 to 2017! Anyway, VW is not the only OE that has an oil consumption issue. GM, Toyota, Subaru, Honda are just a few that also have problems. We had one of our customers with a Subaru return to the dealer due to a high consumption and had a new motor installed for free under warranty. Many Camry hybrid owners, including one of ours, have received the complete engine assembly replacement along with catalytic converters for free. A Toyota TSB (Technical Service Bulletin) states that some 2006 to 2011 model year vehicles equipped with the 2AZ-FE engine may exhibit engine oil consumption issues and a P0300 DTC. The fix for this issue is the replacement of an updated piston assembly that has been changed to minimize oil consumption. Some other issues that I will cover in this article related to oil are the high failure rates of timing chains and related components. There have been studies conducted into the abnormal wear of timing chains, gears and the other components that has been linked to poor oil quality. The oil quality is a big factor in the accelerated wear of the previously mention components. Besides low oil quality, oil level, volume, pressure, viscosity, and the use of oils that don’t meet specifications, there are oil additives that can accelerate timing chain and component wear. The goal in this article is not to provide you with all the TSBs on oil consumption or timing chain problems since that would be redundant to information you can find in your shop’s service information system. With that said, you might want to search “oil consumption” next time you’re logged in! 

Case study time

A 2009 Chevy Traverse 3.6L with a check engine light on, along with the following DTCs; P0017 (crankshaft position exhaust correlation Bank 1) (Figure 3), P0300, P0301, P0303 and P0306 came in. Since we know that this engine is known for engine related DTCs that are caused by timing chain issues we know what we have to check. Rather than spending time diagnosing ignition or fuel issues we are going to concentrate on the mechanical side. The 3.6L engine that is in our problem vehicle has known issues related to timing chain, gear and timing chain guides. In fact, GM will replace the damaged components at no charge up to 120K.  

Figure 3
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