Maximus
11-29-05, 12:02 AM
Preventive maintenance may be a dirty subject in some people's minds, but it's a perfectly acceptable and politically correct means of keeping vehicles in good running condition. Checking fluid levels regularly and changing the fluids and filters periodically can minimize the risks of breakdowns and prolong the life of the engine, transmission, cooling system and brakes. So if you are driving a "maintenance challenged" vehicle, isn't it about time to start paying closer attention to the fluids and filters?
OIL
Let's start with one of the most important fluids of all: motor oil. It not only lubricates the engine, but also cools, cleans and protects it. But the oil itself can't do all of these jobs without some help. Nearly half a pint of various additives are added to the typical quart of oil to improve the oil's ability to resist heat, friction, oxidation and contamination.
Short trip driving is especially hard on oil because the engine never warms up enough to boil off the moisture that accumulates inside the crankcase. The moisture comes from combustion gases that blowby the piston rings (the older the engine, the greater the amount of blowby). Most of these gases are removed by the Positive Crankcase Ventilation (PCV) system. But in a cold engine much of the moisture condenses and ends up in the oil. Water reacts with oil to form sludge and acids, and the result is accelerated engine wear.
The only way to get rid of the accumulated moisture, acids and sludge is to change both oil and filter. The filter only removes suspended solids such as dirt, carbon and metal particles -- not moisture, acids or sludge.
The oil and filter change intervals recommended by the vehicle manufacturers vary depending on the vehicle application and how the vehicle is driven. For "normal service" (which means mostly highway driving, NOT short trip city stop-and-go traffic driving), the scheduled maintenance intervals for changing the engine oil and filter range from 3,000 to as much as 7,500 miles, with the time interval being up to one year. Some vehicle manufacturers even say it's okay to replace the oil filter at every other oil change rather than every oil change.
But if you study the maintenance recommendations closely, most vehicles come under the "severe service" schedule, which generally calls for oil and filter changes every 3,000 miles or six months, whichever comes first-which is the same recommendation most aftermarket experts make. Severe service is short trip driving (7 miles or less, especially during cold weather), towing a trailer, or driving in dusty conditions.
If a newer low mileage engine is driven mostly on the highway, you can probably get away with the longer service intervals. But as an engine accumulates miles, it experiences more blowby which dumps more moisture and fuel into the crankcase. For this reason, engines with more than 70,000 miles should not use the extended oil change intervals regardless of how they're driven. Some engines, such as diesels, suffer more blowby than others so they typically require more frequent oil and filter changes. For most passenger car and light truck diesels, 3,000 miles is the recommended interval for all types of service.
Turbocharged engines likewise require more frequent oil changes because of the high temperatures encountered in the turbocharger bearings. A turbo can spin at tremendous speed (over 100,000 rpm in many instances). This, combined with the heat of the exhaust gases passing through the housing, creates an environment that accelerates oxidation of the oil. When the engine is shut off, for example, the temperatures inside the turbo bearing housing can soar to the point where it "cokes" the oil, forming hard black crusty deposits that can damage the turbo. Because of this, the recommended oil change interval for most turbocharged engines is 3000 miles or six months. The motor oil should be "turbo-approved" for such applications.
OIL RECOMMENDATIONS
What type of oil should you use? Follow the viscosity recommendations in your vehicle owner's manual. Most vehicles today are factory-filled with 5W-30 because 5W-30 improves cold starting, fuel economy, and allows the oil to reach critical upper valvetrain components in overhead cam engines more quickly than heavier viscosity oils. Most vehicle manufacturers also approve 10W-30 for year-round driving. Yet many people prefer 10W-40 or even 20W-50 because they believe the higher numbers provide better protection-which they do at higher temperatures. But GM isn't keen on 10W-40 because they say it tends to break down more quickly than 10W-30 and can gum up the rings. And 20W-50 is too thick for cold weather (below 32 degrees).
You might upgrade to a synthetic motor oil or a synthetic blend. Synthetics are more expensive, but provide superior hot and cold temperature performance compared to petroleum based conventional motor oils. They are especially good for turbocharged and high output engines. Synthetic oils also experience less viscosity breakdown over time. Even so, users should stick to their normal oil and filter change intervals for maximum engine protection. You might also suggest a crankcase oil additive. Some additives are designed to reduce oil consumption in older, high mileage engines. Others, such as the teflon-based crankcase treatments, are designed to reduce engine wear.
OIL FILTER
An engine's main line of defense against abrasion and the premature wear it causes is the oil filter. The filter's job is to remove solid contaminants such as dirt, carbon and metal particles from the oil before they can damage bearing, journal and cylinder wall surfaces in the engine. The more dirt and other contaminants the filter can trap and hold, the better.
In today's engines, all the oil that's picked up by the oil pump is routed through the filter before it goes to the crankshaft bearings, cam bearings and valvetrain. This is called "full-flow" filtration. In time, though, accumulated dirt and debris trapped by the filter begin to obstruct the flow of oil. The filter should be changed before it reaches this point because if the bypass valve is forced open, unfiltered oil will go to the engine.
Though many vehicle owner's manuals say filter replacement at every other oil change is acceptable, most professional technicians recommend changing the filter at every oil change. Why contaminate the clean oil with up to a quart of dirty oil? And why risk expensive engine damage if the old filter is on the verge of clogging up? A new oil filter is cheap insurance against premature engine wear.
Make sure you get the correct oil filter for your engine. In other words, follow the application listing in the oil filter supplier's catalog. Don't try to match filters by external appearances alone. Some filters have SAE threads while others have metric threads. Many overhead cam engines also require a filter that has an "anti-drainback" valve to prevent oil from draining out of the filter when the engine is shut off. This allows oil pressure to reach critical engine parts more quickly when the engine is restarted. Filters that are mounted sideways on the engine typically require an anti-drainback valve.
OIL
Let's start with one of the most important fluids of all: motor oil. It not only lubricates the engine, but also cools, cleans and protects it. But the oil itself can't do all of these jobs without some help. Nearly half a pint of various additives are added to the typical quart of oil to improve the oil's ability to resist heat, friction, oxidation and contamination.
Short trip driving is especially hard on oil because the engine never warms up enough to boil off the moisture that accumulates inside the crankcase. The moisture comes from combustion gases that blowby the piston rings (the older the engine, the greater the amount of blowby). Most of these gases are removed by the Positive Crankcase Ventilation (PCV) system. But in a cold engine much of the moisture condenses and ends up in the oil. Water reacts with oil to form sludge and acids, and the result is accelerated engine wear.
The only way to get rid of the accumulated moisture, acids and sludge is to change both oil and filter. The filter only removes suspended solids such as dirt, carbon and metal particles -- not moisture, acids or sludge.
The oil and filter change intervals recommended by the vehicle manufacturers vary depending on the vehicle application and how the vehicle is driven. For "normal service" (which means mostly highway driving, NOT short trip city stop-and-go traffic driving), the scheduled maintenance intervals for changing the engine oil and filter range from 3,000 to as much as 7,500 miles, with the time interval being up to one year. Some vehicle manufacturers even say it's okay to replace the oil filter at every other oil change rather than every oil change.
But if you study the maintenance recommendations closely, most vehicles come under the "severe service" schedule, which generally calls for oil and filter changes every 3,000 miles or six months, whichever comes first-which is the same recommendation most aftermarket experts make. Severe service is short trip driving (7 miles or less, especially during cold weather), towing a trailer, or driving in dusty conditions.
If a newer low mileage engine is driven mostly on the highway, you can probably get away with the longer service intervals. But as an engine accumulates miles, it experiences more blowby which dumps more moisture and fuel into the crankcase. For this reason, engines with more than 70,000 miles should not use the extended oil change intervals regardless of how they're driven. Some engines, such as diesels, suffer more blowby than others so they typically require more frequent oil and filter changes. For most passenger car and light truck diesels, 3,000 miles is the recommended interval for all types of service.
Turbocharged engines likewise require more frequent oil changes because of the high temperatures encountered in the turbocharger bearings. A turbo can spin at tremendous speed (over 100,000 rpm in many instances). This, combined with the heat of the exhaust gases passing through the housing, creates an environment that accelerates oxidation of the oil. When the engine is shut off, for example, the temperatures inside the turbo bearing housing can soar to the point where it "cokes" the oil, forming hard black crusty deposits that can damage the turbo. Because of this, the recommended oil change interval for most turbocharged engines is 3000 miles or six months. The motor oil should be "turbo-approved" for such applications.
OIL RECOMMENDATIONS
What type of oil should you use? Follow the viscosity recommendations in your vehicle owner's manual. Most vehicles today are factory-filled with 5W-30 because 5W-30 improves cold starting, fuel economy, and allows the oil to reach critical upper valvetrain components in overhead cam engines more quickly than heavier viscosity oils. Most vehicle manufacturers also approve 10W-30 for year-round driving. Yet many people prefer 10W-40 or even 20W-50 because they believe the higher numbers provide better protection-which they do at higher temperatures. But GM isn't keen on 10W-40 because they say it tends to break down more quickly than 10W-30 and can gum up the rings. And 20W-50 is too thick for cold weather (below 32 degrees).
You might upgrade to a synthetic motor oil or a synthetic blend. Synthetics are more expensive, but provide superior hot and cold temperature performance compared to petroleum based conventional motor oils. They are especially good for turbocharged and high output engines. Synthetic oils also experience less viscosity breakdown over time. Even so, users should stick to their normal oil and filter change intervals for maximum engine protection. You might also suggest a crankcase oil additive. Some additives are designed to reduce oil consumption in older, high mileage engines. Others, such as the teflon-based crankcase treatments, are designed to reduce engine wear.
OIL FILTER
An engine's main line of defense against abrasion and the premature wear it causes is the oil filter. The filter's job is to remove solid contaminants such as dirt, carbon and metal particles from the oil before they can damage bearing, journal and cylinder wall surfaces in the engine. The more dirt and other contaminants the filter can trap and hold, the better.
In today's engines, all the oil that's picked up by the oil pump is routed through the filter before it goes to the crankshaft bearings, cam bearings and valvetrain. This is called "full-flow" filtration. In time, though, accumulated dirt and debris trapped by the filter begin to obstruct the flow of oil. The filter should be changed before it reaches this point because if the bypass valve is forced open, unfiltered oil will go to the engine.
Though many vehicle owner's manuals say filter replacement at every other oil change is acceptable, most professional technicians recommend changing the filter at every oil change. Why contaminate the clean oil with up to a quart of dirty oil? And why risk expensive engine damage if the old filter is on the verge of clogging up? A new oil filter is cheap insurance against premature engine wear.
Make sure you get the correct oil filter for your engine. In other words, follow the application listing in the oil filter supplier's catalog. Don't try to match filters by external appearances alone. Some filters have SAE threads while others have metric threads. Many overhead cam engines also require a filter that has an "anti-drainback" valve to prevent oil from draining out of the filter when the engine is shut off. This allows oil pressure to reach critical engine parts more quickly when the engine is restarted. Filters that are mounted sideways on the engine typically require an anti-drainback valve.