WHEN REMOVING THE GASOLINE CAP, ROTATE SLOWLY ONLY FAR ENOUGH TO ALLOW PRESSURE TO RELEASE. AFTER "HISSING" SOUND STOPS, COMPLETE THE REMOVAL OF THE CAP.

General Chassis Topics (Gasoline-Powered Models Only)

DO NOT UNDER ANY CIRCUMSTANCES OPERATE ANY ENGINE WHILE SLEEPING.

Oils

When it comes to engine oil there really isn't too much to be concerned about.  The American Petroleum Institute (API) has an engine oil licensing and certification system which essentially gives engine oils a quality rating.  Basically, the API website will give you all the information you need to select the proper oil for your engine.  It will also give you a listing of all licensed engine oils by brand name so that you may use the proper grade of your favorite oil.

With respect to engine oil additives, you should be aware that the API licensed engine oils contain all the additives which are necessary for satisfactory performance in running engines (as opposed to stored engines).  Neither the oil manufacturers nor the automotive manufacturers recommend the use of engine oil additives.  In some cases, the use of additives could void the engine warranty.

Unfortunately, there are also many myths surrounding gasoline and diesel fuels.  Perhaps the most common myth involves gasoline octane.  A significant portion of the population believes that the higher the gasoline octane, the better the gasoline.  The thinking is that higher octane means more power and better fuel economy.  The truth of the matter is that octane has no relationship to fuel quality, power, or economy.  Engine design determines what gasoline octane is required for a particular engine.  Therefore, it makes sense to use gasoline with the octane specified by the manufacturer.  The ONLY reason to use a higher octane than recommended by the engine manufacturer is to stop engine knocking and the cause for the engine knocking should be determined quickly to prevent engine damage.  Recently the Federal Government cited several major oil companies for misleading advertising with respect to gasoline.  Virtually all of these ads implied that using premium grade gasoline in your car would give you more power and all round better performance.  Several oil companies have had to refrain from making misleading statements and to promulgate information that you should use the grade of gasoline recommended in your owner's manual.

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Which oil is right for you?

For automotive gasoline engines, the latest engine oil service category includes the performance properties of each earlier category. If an automotive owner's manual calls for an API SG or SH oil, an API SJ oil will provide full protection. For diesel engines, the latest performance category usually - but not always - includes the performance properties of an earlier performance category.

It's okay to switch brands of engine oil, as long as the new oil is a premium grade. If you need to add oil, however, try to add the same brand.

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Synthetic Oils 

Synthetic oils have no advantage what so ever.  They were developed for the military because it will flow at very low temperatures. They can also handle 400 degrees before they fail, instead of 270. But a 10-40 oil is good to 11 degrees below zero, and we're typically not in temperatures that cold. And engine temperatures almost never exceed 250 degrees. The additives we add to regular oil are the same ones that are added to synthetics. The additives DO wear out whether they're in mineral based oil or synthetic oil. That's why we change the oil. The oil itself never wears out.

Additives break down and you can't see it. Thus you can't go by a continuing "clean looking" oil.

Synthetics work well under both low and high temperatures. Better for starting and driving in cold temperatures. Less evaporation. Less viscosity change with temperature swings. Works well in all temps. Friction modifyers means more horepower, better fuel economy.

Synthetic Oil Disadvantages: Poor break in qualities. Don't use it while it's on warranty. Higher cost. 25K oil change. Can't mix w/regular oil or w/other brands. Okay to drain and go back. [Note: Other classes insist synthetics need to be changed with the same frequency as regular oil.]

Then we come to "SAE 5W-30".  The statement is made that, if you're in Arizona, 15-40 might be better.  It won't break down as fast in hot temperature.  Multi-viscosity oils involve a tradeoff."  First, engine oils don't "break down" per se.  They do oxidize from being exposed to high temperatures over prolonged periods of time, but this has nothing to do with viscosity.  All oil will get thinner the hotter it gets.  To minimize this thinning effect viscosity index improvers are blended into the oil.  Thus, a 5W-30 oil will pour like a 5W oil when it's cold and will retain the thickness of an SAE 30 oil when it's hot.  The same rules apply to the 15W-40 oil.  Making a statement to the effect that multi-viscosity oils involve a trade-off without indicating what that trade-off might be is just plain irresonsible.  The fact of the matter is that virtually all gasoline and diesel engine manufacturers recommend multi-viscosity oil in their engines.
 
The statement that teflon, graphite, or silicon (which is sand) are used to make "energy conserving" oils is just pure baloney.  The truth is that the friction modifiers noted in conjunction with "Energy Conserving II" are what is used in all "energy conserving" oils.
 
Any instructor who says that additives are "good" just doesn't know what he's talking about.  Any oil which meets API Classification SJ/CH already has all the additives it needs, no matter how much or how little it costs.
 
When the author discusses synthetic oils he really displays his ignorance.  "5 years ago wouldn't have recommended synthetic oils.  Now they are quite good--but so good that can't use it until engine is broken in".  Mobil Oil has been selling synthetic oils for over 25 years.  When the Alaskan pipeline was being built (a lot more than 5 years ago)  Mobil supplied synthetic lubes for all of the equipment used to build it.  That included engine oils, transmission oils, gear oils, hydraulic oils, and greases.  The statement that synthetic oils are now so good they can't be used until the engine is broken in is also false.  There is no valid reason for not using synthetic oils in an engine from day 1.  In reality, however, engine manufacturers are not going to use synthetic oils in new engines because of the cost factor.  And when a motorhome purchaser takes possession of his new motorhome it is likely to already have several hundred miles on it and is "broken in".
 
"Park MH for winter, you have acid in oils, and they tend to corrode.  If you change oil before storage, you get condensation which causes corrosion.  For this reason, change at the beginning of the season.  Best solution would be to change at end of season, and again at the beginning of the season, but that's probably impractical a well as expensive."  Now what does all that mean?  The correct recommendation is to definitely change oil and filter before storage.  Then, don't dump quarts (or gallons) of brand new oil in the spring.  Any condensation which has formed in the engine over the winter hasn't affected the oil at all and any corrosion caused by that condensation has already occurred.  Just start the engine and drive the vehicle until the engine is fully warmed up (it will take about 20 miles of driving) at which time any condensation which has formed in the engine will be evaporated and driven off.  NOTE:  The engine temperature gauge (which only measures coolant temperature) can indicate normal operating temperature while the engine oil is still cold.  The engine isn't fully warmed up until the engine oil temperature has reached its maximum operating temperature.

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Cummins Engines

Diesel engines are very durable, but they DO need to be maintained. Items such as the quality of oil and change interval have a significant impact. There are many B series engines in Dodge pickups delivering fifth wheels which have over 500,000 miles. They are working year round. Motorhomes typically don't accumulate that much mileage in a few years, and time takes its toll. Actually, the engine likes to work hard. They're happier in a motorhome than a pickup.

All discussion of maintenance assumes PREMIUM materials are used. Major suppliers put out several grades of product. There are premium grades of oil, and there are lesser grades. There are differences because the manufacturers are aware that some folks buy based solely on cost. Engine oil has certain specifications. But these specifications are MINIMUM standards required to carry the label. Filters are the same story. The premium brands do much better. This is also true with respect to air and fuel filters.

Engines wear out primarily because of abrasives. There are other types of abrasives than dirt. Abrasives are things that are in places they shouldn't be. The main thing is to filter that stuff out. We can't stop it all, but with premium products we can minimize the effect.

Coolant has a limited lifespan due to degradation. It eventually forms acids that cause system damage. Unfortunately, this is a little understood fact. Hoses and O rings can be damaged by degraded coolant. On the C series one can add chemicals to slow the process. C series need supplemental coolant additives (SCA's). The B series engines are different, and don't require the SCAs, unless you're running high mileage -- in which case you'll extend the service life of the coolant and not have to change the coolant at the recommended mileage interval.

TIP: There are really no problems, from a Cummins engine point of view, to exhaust brakes. They simply save on service brakes. But they do require heavier valve springs. Most of the kits include them.

Air systems: Cummins recommends ONLY paper elements. If we stop all the dirt, we'll also stop air. Air filters cause air restrictions. Once the air restriction increases, the air filter needs to be changed. There is more harm done by pulling the air filter out, looking at it, blowing on it, etc. , than in leaving it in place and taking the reading from the outside gauge. That's why the outside gauge is there. The symptoms of air restriction are smoke and poor fuel mileage. A new filter will have an air restriction which equals approximately 12 inches of water. When it gets to 25, it needs changing. But this will be indicated on the outside gauge.

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How to deal with RVs in storage

If you're going to store the unit over a season, is it better to change the oil before or after? Answer, definitely before.

Run it once a month to circulate oil. Better yet, drive it around the block. If it's been sitting longer than that, crank with the fuel off (disconnect the fuel solenoid wire) When the oil pressure comes up, reconnect the wire and light it.

Cummins recommends filling the filter with oil at the oil change, rather than simply installing a dry filter. But be certain that it's filled with the same premium oil.

Start up: Let it idle for a couple of minutes before starting out. This will get oil to all the places that need it and get some heat to the engine. Don't let it idle excessively. Drive modestly for the first few minutes. Once the engine hits 160 degrees, its ready for anything.

Cool down time: When you pull into a rest stop after driving under full load, let the engine idle for five minutes to cool down (or until the exhaust temperature returns to approximately 300 degrees). The only thing that cools the turbocharger is the oil flowing through it. When the engine is turned off, the cooling effect is terminated, which is prejudicial to a turbocharged diesel. Pyrometers and boost gauges aren't essential for modern modern diesel engines. They're nice, but not essential. They are really trouble shooting devices. A boost gauge will begin to fall back when the fuel filter needs changing; and the pyrometer will help give you a more precise reading on when to shut the engine down.

Performance packages for the Cummins: All of the kits he's read about end up saying that at the end they turn the fuel screw on the pump to slightly overfuel it. If the screw is turned, the manufacturer says the warranty is voided. It's turning the fuel screw on the pump that causes the power increase -- not all the stuff that he's read are in the kits. [See notes on Monday's class: "Engine Performance"]

The B or C engines can be run wide open. The maximum horsepower will be at the rated speed. It can go close to 4,000 rpm before damage occurs. Turbos are happiest when the engine speed is between the peak torque and maximum horsepower. Try to drive within that range.

Black smoke: Usually indicates an air intake restriction or leak, exhaust restriction, or fuel restriction. A puff of smoke on acceleration is normal. It can also occur when the engine is below its intended operating range.

What about fuel additives to clean the injectors? Usually on the mid-range engines they aren't required. The low sulfur fuel has had no negative effect on the Cummins engines. The impact on fuel economy is so small that it's not measurable. In general, Cummins recommends against additives. Most will have no effect at all, and some of them can even have a negative effect.

Fuel consumption in the winter months is much worse than in the summer. Expect about one mpg difference. All the components (including tires) are running colder, and it takes more horsepower to move through thicker oils. Winds and other weather conditions are also a factor.

The C series engine will come in different horsepower configuration. It's not merely a change in the calibration of the fuel screw. The entire engine is redesigned to achieve the target horsepower that is required for a particular application.

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Engine Oils

Oil -- What are you putting into your motorhome or tow vehicle. When you go to Wal Mart, can you buy off the shelf? What about diesel -- and turbo diesel?

SAW = Society of Automotive Engineers. Sets weight classifications. Non-profit standards setting. API is American Petroleum Institute, they set quality standards.

Just in past year, the classifications have changed. So beware of "sale on oil" signs, because it may likely be a sale of outdated oil. It may be a bargain, but not suitable for your rig.

API "SJ/CD" is current standard. Don't buy anything with "less than" SJ. Can use SJ on any vehicle, but can't use "SH" oil on many 1999 vehicles.

Next letter is "C" which is "commercial" or heavy duty. Last letter, "D" is latest in series.

Not all oils work in diesel engines.

"SAE 5W-30"

The "W" means winter. The lower the number before the "W", the easier it will pour in cold weather. If you're in Arizona, 15-40 might be better. It won't break down as fast in hot temperature. Multi-viscosity oils involve a tradeoff. If you're using a particular number use same when you add oil.

Oil puts friction in your engine. The thicker the oil, the less fuel economy -- but the tradeoff in terms of engine life. Some mfgrs say use 5/30 to get you better fuel economy -- but the tradeoff may not be worth it in terms of engine life.

"Energy conserving" -- additives which guarantee at least 1.5% better fuel economy. These are teflon, graphite, or silicon. -- all there to make things slippery to get better fuel economy.

"Energy Conserving II" -- means you get at least 2.7% more fuel economy. This means "friction modifyers".

Instructor says additives are "good", and help engine as well as

You get what you pay for in engine oils! The cheaper oils are cheaper for a reason.

Do NOT add friction modifyers (e.g., Slick 50) when engine is new -- b/c engine won't break in. First 5-10K, rings won't seat -- and you'll have an oil burning engine. Don't add syntetics or additives while under warranty.

5 yrs ago wouldn't have recommended synthetic oils. Now they are quite good -- but so good that can't use it until engine is broken in.

Service intervals. Regular duty versus severe duty. Regular duty is freeway in moderately warm weather with no dust. Virtually no one is "regular duty". But that is only to sell cars. You should ALWAYS consider you're in heavy duty/severe use. So change oil at the "heavy duty" miles rating. Should definitely change oil filter at each oil change.

Change diesel engine oil more or less than gas? No difference.

Park MH for winter, you have acid in oils, and they tend to corrode. If you change oil before storage, you get condensation which causes corrosion. For this reason, change at the beginning of season. Best solution would be to change at end of season, and again at the beginning of season, but that's probably impractical as well as expensive.

Don't run the engine every few weeks during the winter. [but catch 22] If you do that, need to drive it a long way. You get condensation in engine, causing rust -- push rods, rocker arms, cam shaft. Old myth. Another is let the engine warm up in winter -- Start it and let it run while you have a cup of coffee. Worst scenario is starting cold engine in winter. More wear on startups and long idling periods. If you do start it, run for an hour. If possible run air conditioner during the winter too.

Diesels -- less harmful to let it run than to start it. Block heaters help a lot. Diesel conditioners are primarily to let the fuel flow better. .

About diesel fuel additives -- with the low Selfware fuels, older diesels may benefit from them. It's not likely additives are useful on newer diesel engines.

Alll gas is not the same. Cheaper gas stations often buy the better gas when there's an abundance of it. But the quality is uneven. Chevron additives are good. Higher octance, less knock in engine. He uses low octane fuel, unless ping/knock, which requires moving up. Octane is more important in hotter temperatures. Hot air offers less oxygen, so need better quality (octane) fuel. pinging hurts engines.

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Antifreeze

50/50 108 degrees. 3 degrees for every pound of pressure. Thus a 15 pound cap = 45 degrees more. But if radiator cap not sealing well, you just lost 45 degrees of boiling. Radiator caps not sealing and thermostat are the two most common problems w/cooling system.

Need for changing coolant every 4 yrs or 60K (kms). Coolant may look clean, but it's starting to do damage. Chemical called back flush which can take out scales. Needs to be flushed before re-fill. Not a do it yourself project.

Hose clamps. Only use worm drive hose clamps -- not sprig, srew tower or twin wire types.

Many thermostats are double stage -- if you have one of these, don't use a single stage thermostat when you change it.

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Propane

Properties of propane. It has no odor by itself. It's clear. An odorant is added, and that's the smell we're all familiar with. It's heavier than air, and thus displaces air. That's why propane detector is usually within a few inches of the floor. It has limits of flammability. 2.5% - 9.5% by volume mixed with air is where it's flammable. Thus when it first leaks out, it's an insufficient "mix" to be explosive. At .5% (by volume) you can begin to smell it.

When you purchase it, it's in a liquid state. Tank gets filled to 80%. Allows for 20% expansion. When vaporized, it expands 270 to 1. Liquid propane "boils" at -44F. If surrounding area is colder than that, it stays in liquid form, and won't come out of tank. Not usually a problem w/propane.

But sometimes it's mixed with butane. Coming home to northern states from AZ with a full tank of butane -- which won't vaporize until it gets above 32F -- can cause a problem, since butane needs to be above freezing to vaporize.

Perfect combustion of propane yields water, carbon dioxide & heat. But often it's not perfect.

Cylinders & Tanks: Cylinders small disposables (like Coleman) up to very large re-useable. If you refinish the outside of a cylinder yourself, use white or off-white color. Dark colors absorb heat, and propane liquid expands 1.5% for every 10 degrees (measured against temp at filling time). Plastic milk cartons make great travel containers for propane tanks when taking them in for refilling. The date on the tank should be w/in 10 years -- and if not, needs recertification. Usually cheaper to dispose of the old tank and purchase a new one. [Note: US is 12 years, Canada is 10 years.]

Recommend don't travel with fridge on. Fridge can retain cold for a full day's travel, so really not needed anyway. New tanks have "OPD", overflow protection device (triangular handle plus outside label). These not only have spit valve, but something that cuts off filling at 80%. Quick connect "QC-1" valve. No more messing around with wrenches. Be very careful with propane. Control each time the gas pipes for leakage after having driven on a bad surface.

Propane cyls & tanks require purging before use, to ensure getting rid of air/moisture. If it's exposed to atmosphere (empty with valve open). Moisture effects pilot lights and other probs. Can save cost of purging. Put anhydrous methanol into container to eat water, and bleed off several times. Then charge w/15# vapor.

Two ways to fill cylinders. By volume -- open set screw, will bleed off when fogs out at 80%. In US they fill by volume, and won't touch a tank w/out it. Also, can fill by weight. Collar shows tear weight -- which is dry weight. Water capacity, mulitply by 42%.

Hoses & Lines. Propane goes to regulator via hoses. They should be flexible, and state on it that it's for LP gas and good to 350#. Look for the label of UL or CGA approval. Some have "O" rings. Check them for cracking. Check hoses for dry cracking as well.

Don't use Teflon tape or lubricant on threads.

Barbeque "single stage" regulators are illegal on RVs. Two stage regulators provide margin of safety. 100# tank pressure goes down to 10-13#; second stage can work much more easily with the low pressure it receives from first stage. Vents must be pointed down +/- 45 degrees. Auto change over lets you open both tanks, point to the primary tank which will be used up first. When it runs dry (propane will now be automatically drawn from the second tank) turn it off, switch pointer to second tank, and you're ready to fill up the empty one.

What a great deal propane is! You get so much for such a small cost. It goes into your tank as a liquid; but it comes out of your tank as a gas. It purposely has an odor which you can detect if there is a leak. It powers your range, refrigerator, hot water heater, and heater. All newer RVers have propane "sniffers", which will sound an alarm if it detects any propane leaks. If you suspect a leak, go outside immediately, turn off the propane at the tank, open all the windows and door, and get an expert to fix it. But these are well made systems, and malfunctions of the propane distribution system is uncommon.

Refrigerator: These are different from what you have in your house. These usually operate on either 120 AC, or propane. And occasionally they will run on DC as well, though that's becoming less common because it causes a significant drain on your batteries. Recommends you not use propane while you're driving, because it's unsafe. Better, shut off propane at the tank whenever you're driving. The only thing you need to do is ensure your rig is reasonably level, so the refrigerator can operate as designed.

Propane regulator: Put a dirt trap (also known as dirt pocket) on your regulator. All home systems have them. It's a 1-2 dollar item, and can save a lot of problems. Not a safety issue. Gives service tech easy access to do pressure check (don't have to disconnect appliances), and can periodically drain residue. .

Leak test -- a great product is kids bubble stuff. Doesn't have the prohibited ammonia.

Furnace thermostats can be adjusted as to cycle (length on). Fine wire is anticipator. Longer the wire, the shorter the cycle. A "normal" set would be for around 3.5 degrees. Likely thermostat needs to be tailored to the needs of the particular RV in which it's installed. A 35 foot motorhome needs to cycle more slowly, as it takes longer to heat up -- than a 10 foot camper. Ideally, furnace should have a chance to cool down between cycles. They are not "continuous duty" furnace motors. Motors are improved, but still probably the weak link in the system.

For dual propane cylinders: The solenoid valve often fails. Don't let anyone replace a propane appliance until you've checked to see whether the solenoid valve is working properly.

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Frequently Asked Questions

Question. What's the story on synthetic engine oils and do you recommend them?

Answer. Synthetic engine oils are superior to conventional engine oils. However, this superiority exists primarily under very low and very high temperature conditions. Synthetic oils will pour more readily at very low temperatures and thus will provide quicker and better lubrication at these temperatures. Likewise, synthetic oils are more resistant to oxidation at high temperatures and thus will provide better lubrication at high engine temperatures. Whether or not you decide to use synthetics, justifying their considerably higher cost is not easy to do. The higher cost can be justified by increasing engine life, which is always difficult to prove. It can also be justified by increasing drain intervals, thus saving on oil costs (if synthetic oil costs twice as much as conventional oil, doubling the drain interval would make the oil costs equal, and, you would actually save money if you increased the drain interval even more), filter costs, and any associated engine downtime costs. A couple of words of caution if you consider increasing drain intervals. First, if your engine is still in warranty you might void that warranty if you exceed the manufacturer's recommended drain interval. Second, the only way you can be sure you're not exceeding a safe drain interval if you go beyond the manufacturer's recommendation is to have the used oil anaylyzed.

Question. I have heard a lot of horror stories about storing diesel fuel like the diesel fuel in my motorhome's fuel tank. What should I do to keep the fuel from decomposing when my motorhome is stored for several months?

Answer. Diesel fuel is far more stable than most people realize. In fact, it's more stable than gasoline because it's less volatile. The primary problem with storing diesel fuel is a bacteria problem. It's a fact that water must be present in the fuel in order for bacteria to grow in that fuel. If you have water in your diesel fuel tank, it will be at the lowest point in the tank. If bacteria are present, they will grow at the interface between the water and the fuel. The obvious solution to the problem is to get rid of the water. You may want to take a tip from the people who sell gasoline and diesel fuel. To insure that they have minimal water in their underground storage tanks, they "stick" their tanks using a stick with water-indicating paste on the bottom of it which they push down to the bottom of the tank. If there is water present, the paste changes color. If water is found, they pump it out by pumping from the bottom of the tank until they don't get any
more water. Depending on the configuration of your motorhome's fuel tank(s), you can do the same thing. Note that water in diesel fuel almost always comes from condensation, so quantities are minimal.

Question. Should I be concerned about using low sulfur diesel fuel and should I use a fuel additive to handle this fuel?

Answer. Low sulfur diesel fuel has been the standard in this country long enough for any problems associated with its use to have been solved. Navistar (International Harvester), for example, specifically recommends AGAINST using any diesel fuel additives. The V8 diesel engine used in full-sized Ford pickups is manufactured by Navistar.

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NOTE: This online manual  is a work in progress and is subject to change at any given time. It is also a generic peace of work and is meant only as a general guide. Each Caravan/RV is distinct and individual in it's own right, do not take anything written here literally as it may or may not apply to the exact Caravan/RV you will be using.

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