You’ve been hearing a lot about higher oil change intervals these days. Maybe you’re wondering: What are the key issues?

Some new vehicle manufacturers are now recommending much higher oil change intervals than they have in the past. As much as 5,000 to 8,000 miles or more. This practice came under scrutiny when four of the largest new car manufacturers announced that owners were experiencing engine damage resulting from these higher oil change intervals.

The manufacturers’ standard oil drain service for particular vehicles was scheduled at around 7,500 miles. People following these recommendations were experiencing engine damage. It turns out that oil sludge was building up. This caused small oil passages to clog and engine parts to fail.

Skipping an Oil Change

What causes oil sludge? It’s a factor of time and mileage. There are hot spots in every engine that cause oil burn off that leads to sludge. Also, water from normal condensation can build up in the oil. This water also creates sludge. Severe driving conditions lead to more rapid sludge formation.

Severe driving includes short trips under four miles or trips under ten miles in freezing conditions. The engine just doesn’t get warm enough for the water in the oil to evaporate.

Severe conditions are at the heart of the problem. Stop and go driving, towing, dusty conditions, heavy loads, very hot or very cold temperatures, a car top carrier – these are all conditions that would suggest that the severe service schedule should be considered.

The severe service schedule has much shorter oil change intervals. People just need to honestly evaluate how they drive to determine if they should change their oil closer to the severe service schedule, or to the standard schedule.

Some cars give oil change reminders. But it’s important to know how that reminder is determined. For some, the reminder simply comes when the standard mileage interval has rolled around. Others use a computer algorithm that takes into consideration the number of cold starts, trip length, engine temperature and so on. It’s programmed to approximate where on the standard/severe service spectrum you fall. Some more expensive vehicles actually have sensors that test the cleanliness and effectiveness of the oil.

For the rest of us, better safe than sorry should be the guiding principle. Talk with your service advisor and work it out together. Find out what kind of oil the factory sends out in your vehicle. Sometimes it’s a premium grade that costs more than standard oil – but it may be what’s needed to meet a higher factory recommended interval.

If you’re realistically conservative, standard grades of oil will take care of you year after year. If you want to push the limits, ask for a premium grade oil to give you extra protection.

So, what happened with those manufacturers with the problems from higher oil change intervals? They ended up extending the engine warranty for parts that were affected by oil sludge. But they had a stipulation – they lowered the oil change interval and the vehicle owner had to provide proof of oil changes at the new lower interval to keep the extended warranty.

And don’t forget to check out our other great auto video tips online at http://autonettv.com/video-library

Nothing in your engine workers harder than your oil.  With hundreds of moving parts, and thousands of explosions every minute, it’s no wonder that engine oil needs to be changed frequently!

You’ve probably heard the old rule of thumb: Change your oil every 3,000 miles/ 5,000 kilometers or 3 months, whichever comes first. But some car manufacturers have introduced extended oil change intervals.  They figure that a modern vehicle driven under the right conditions can go for 5,000 miles/8000 kilometers or more between oil changes.

The key phrase here is “under the right conditions”. If you look at your owner’s manual, you’ll see two different maintenance schedules: one for “normal” driving conditions and one for “Severe Service”.  Severe service driving conditions include stop and go, short trips, towing, hauling, hot, cold, and dusty driving. That’s why at AutoNetTV we often refer you to the severe service schedule in your owners’ manual, because, for most of us, that’s the way we use our cars in everyday life.

Recently, four of the largest auto manufacturers in the world have extended engine warranty coverage for engine damage caused by oil sludge resulting from longer oil change intervals.  They found that real-world conditions require more frequent oil changes than the 7,500mi/12,000 km interval they were recommending.  They subsequently recommended more frequent oil change intervals and proof of timely oil changes in order to qualify for the extended warranty.

Oil sludge is the culprit. Sludge is oil that has turned to a thick, jelly-like consistency.  Sludge can block passages in the engine, preventing oil from lubricating vital engine parts.  Parts wear more quickly and may fail prematurely.

Sludge is caused by several factors.  The first one is simply – time. The engine oil is contaminated by exhaust gas that eventually leads to sludge. That is where the recommendation to change your oil at least every three months comes from. Sludge can also come from oil that gets contaminated by water from normal condensation. A few minutes of driving at freeway speeds allows the oil to heat up enough for the water to evaporate. The problem is we often run errands or take other short trips that don’t allow the engine to warm up enough for the water to evaporate.  This is especially true in winter. Sludge also forms when the engine gets too hot, causing the oil to breakdown.  Stop and go summer driving, towing and hauling are all prime conditions for creating harmful sludge.  And every engine has hot spots that create sludge.

Given all of these factors, estimating when to change your oil is pretty complicated.  A couple of manufacturers have computer programs built into their vehicles that record the number of cold starts, how many times the cylinders fire, engine temperature and other factors.  From that, the computer estimates when you should change your oil and flashes a warning.  But what if you do not have a vehicle with this feature? How do you know when to change your oil? We’re not sure you really can.  Which is why it is better to be safe than sorry.  3,000 mi/5,000 km or three months – whichever comes first – talk with your service advisor and see if that’s a good recommendation for the way you drive.

A lot of our viewers have asked whether or not they should use their severe service maintenance schedule, which is listed in their car owners’ manual.  It can be confusing.  Let’s clear the air on this subject. Cricket Killingsworth is from QMI/Heartland, a manufacturer of automotive products and fluids. She’s been in the automotive business for 20 years and is a speaker, a trainer, and a writer.  Cricket says there’s so much confusion on this topic because, “Most owners’ manuals actually have two maintenance schedules.  Sometimes these are called ‘regular service’ and ‘severe service’.  Sometimes they’re simply called Schedule 1 and Schedule 2.  A severe service schedule recommends that things like oil changes, air filter replacement, and transmission service be done more often:  either in fewer miles or in less time.”

Manufacturers create these specific schedules for each vehicle they make.  So there isn’t one generic schedule that applies to all cars.  In addition to your owners’ manual, service centers subscribe to information services that provide the maintenance schedules for every vehicle – so they can help you know when to take care of needed services. Below is a typical definition for severe service.

• Most trips are less than four miles
• Most trips are less than ten miles and outside temperatures are below freezing
• You drive in very hot weather
• The engine is at low speed most of the time (not on the highway)
• Stop and go driving
• You operate your vehicle in dusty or muddy conditions
• You tow a trailer, regularly carry heavy loads or carry a car-top carrier

It’s common sense:  Just a few minutes at freeway speeds allows the moisture in the oil to evaporate.  Very short trips, or trips of less than ten miles when it’s very cold, don’t allow the engine to heat up enough to get rid of the water.  And water in the oil leads to damaging sludge.  Also, towing and heavy loads raise operating temperatures and cause fluids to breakdown more quickly.  Dusty and muddy driving means that more dirt will get past the air filter to contaminate the fuel system and engine oil.

The bottom line is that you need to decide for yourself if the regular or severe service schedule is right for you, based on your driving.  Look at your owners’ manual, or talk with your service advisor who can help you know which schedule to follow.

Here is what a fleet manager said recently:  “Since city miles are generally tougher on vehicles than highway miles, we use the manufacture’s serve service schedule as the basis for our preventative maintenance program.  We massage those schedules over time, increasing or decreasing the service intervals so that they make the most sense.  There is a little bit of art to go along with the science.”

Make an honest evaluation of your driving habits.  Unless you do mostly highway driving in moderate weather, you’ll likely have a fairly good amount of severe service mixed in.  Some people just want to play it safe and follow the severe service recommendations, rather than analyzing how they drive each month.

The energy from exploding fuel is what powers your engine.  But some of the vapors from the explosions escape into the lower part of the engine, called the crankcase.  The crankcase is where your engine oil hangs out. These gases are about 70% unburned fuel.  If the gases were allowed to stay in the crankcase, they would quickly contaminate the oil and turn it to sludge.  Sludge is one of the biggest enemies of your engine, clogging it up, eventually leading to expensive failures.  Also, the pressure build up would cause seals and gaskets to blow out. Therefore, these gases need to be vented out.

Gasoline engines used to simply have a hose that let the poisonous fumes vent out into the air.  In 1963, the federal government required gas engines to have a special one-way value installed to help reduce dangerous emissions.  Diesel engines are not required to have these valves.

The positive crankcase ventilation, or PCV, valve routes crankcase gases through a hose and back into the air intake system where they are re-burned in the engine.  Fresh, clean air is brought into the crankcase through a breather tube.   It’s really a pretty simple system, but does an important job. The re-circulating air removes moisture and combustion waste from the crankcase, preventing sludge.  This extends not only the life of your oil, but the engine as well.  The PCV relieves pressure in the crankcase, preventing oil leaks.

Eventually, the PCV valve can get gummed up.  Then it can not move enough air through the engine to keep it working efficiently.  If the PCV valve is sticking enough, you could have oil leaks, excess oil consumption and a fouled intake system.  If you experience hesitation or surging or an oil leak, it may be a sign of PCV value problems.  Your owners’ manual may give a recommendation for when the PCV valve should be replaced – usually between 20,000 mi/32,000 km and 50,000 mi/80,000 km.  Unfortunately, some manufacturers don’t list a recommendation in the manual, so it can be easy to overlook.

Many PCV system problems can be diagnosed with a visual inspection.  Fortunately, PCV value replacement is both quick and inexpensive.  Proper oil changes will greatly extend the life of the PCV valve.  Skipping a few recommended oil changes can allow varnish and gum to build up in the valve, reducing its efficiency. So now when your service technician tells you its time to replace your PCV value, you will know what he’s talking about.  If you have had your car for a while and this is the first you’ve ever heard of a PCV value, ask your tech to check yours out.