Remember when proper engine care meant an oil change every 1500 miles? And an oil and filter change at 3000 miles? Oil was really cheap then.
So much has happened in the automotive world since then. For one thing, engines have had to become far more efficient:
- Precisely machined and carefully engineered components.
- Higher compression ratios.
- Precise fuel metering using electronic fuel injection.
- Exacting control of emissions during all phases of engine operation.
In addition, fuel and oil have become more expensive – not so much in North America but certainly in a lot of the rest of the world.
Finally, there has been a marketing push by manufacturers to tout their vehicles as low maintenance – always lower than the competition.
These trends have pushed the recommendations for oil changes to longer and longer intervals. Expensive synthetic oils make oil changes pricey. They also make it possible to keep oil in the engine for longer because they have better detergent and dispersant properties. The recommendation from most manufacturers is for very low viscosity oils. This helps reduce friction losses in the engine, even when cold, thus increasing fuel efficiency. It also means that unburnt hydrocarbons and other sludge forming compounds that inevitably end up in the sump remain better suspended.
Many auto manufacturers now recommend 6,000 mile or 7,500 mile oil change intervals, and some have even gone to 15,000 miles. However, if you read the owner’s manual carefully, these very optimistic intervals are recommended for a vehicle in “normal use”, whereas “severe use” of the vehicle often halves that mileage, whatever it might be. And if you read the description of “severe use” you often find that it’s pretty much what we all do every day: Stop and start city driving, cold starts and short runs, hot weather with climate control on full, towing a trailer and so on.
The trends toward making vehicles increasingly hands-free has led to another development – the proliferation of electronic oil level sensors; these are usually coupled with a system for detecting the need for oil change. So, the old-fashioned oil dip-stick is gone. Some lights on the dashboard tell you if you need to add oil, and other instruments tell you if you’re due for an oil change.
Multiple technologies are in use or under experimentation in determining oil quality. Some of the major examples of this:
- General Motors introduced the Oil-Life System in some 1998 models and has been expanding it into all its lines. This system does not actually monitor the oil itself. Instead it calculates current oil condition based on engine temperature during various operation phases.
- Daimler-Chrysler (while Mercedes-Benz and Chrysler were merged in the late 1990s and early 2000s) used Flexible Service System (FSS) to monitor oil condition based on its conductivity.
- Bosch GmbH developed a piezoelectric sensor system, installed in the oil sump, which continually monitors oil viscosity, conductivity and temperature.
In theory, and especially if applied to newer models, these novel ways of cutting back on potentially wasteful maintenance work for a few years. But we have no way to check oil level or visually inspect oil quality (no dipstick) and the market-driven owner’s manual folks tell us regular oil changes are a thing of the past. So, after the initial few years we end up with sludge buildup in oil sumps; clogged oil filters leading to oil bypassing the filter element; oil control rings becoming stuck in the piston skirts leading to additional sludge buildup or oil dilution; gunked up variable valve timing mechanisms and camshaft phasers. And all this on recent models of many makes.
Some of the largest auto manufacturers, responding to the spate of failed engines due to lack of oil changes, have extended the time span for factory warranty on their newer engines. But to qualify for the extended warranty, owners must show that they followed the factory recommendations for oil change – based on the oil-condition sensors that the factory provided. And the recommended oil change intervals have been reduced on the replacement engines.
It is now possible to circumvent a major part of the problems caused by infrequent oil changes by using advanced pour-in oil treatment. A chemical such as the ATS oil system cleaner breaks down carbon deposits and sludge in both gasoline and diesel engine components. If used on a regular basis, such an oil system cleaner reduces problems with sticking piston rings, lifters, camshaft phasers, oil control valves, and timing chain tensioners. It also flushes gunky oil deposits away from oil pump pick up screens.