Gas versus Diesel

Gas versus diesel powered motorhomes and tow vehicles.  The question always comes up.  And, unfortunately, there is no easy answer.  But there are some distinct advantages and disadvantages to each the potential buyer should be aware of.  Gasoline and diesel engines behave differently, have different strong points and different weaknesses.  Personal preferences play a significant role in choosing between gasoline or diesel powered RVs and tow vehicles.

There have even been long standing debates over whether gasoline or diesel engines or more environmentally friendly.  Unfortunately, there has not been any conclusive answer.  Turns out the issue is more complex than most people could possibly imagine or understand.  Each technology has its benefits and its problems.  Each type of fuel yields different results, with gasoline winning in some categories and diesel in others, but neither can be conclusively declared better than the other in all categories.  And, of course, there are those who simply want to ban the use of ALL fossil fuels, but we will leave that for another discussion.

Gasoline powered vehicles are generally less expensive to purchase than diesel.  Gasoline engines typically deliver more horsepower from a given displacement.  Gasoline engines usually provide faster acceleration  than diesel engines. They are usually less expensive to work on also.  An oil change on a gasoline vehicle is typically around $50 or less.  But they generally get poorer fuel economy and don't have the high torque of diesel engines.  If you have gasoline powered motorsports toys you can use your spare gas in your vehicle if you run low.  I've even burned pre-mix 2-stroke fuel in my truck in a pinch with no negative side effects.  Gasoline powered chassis usually have the engine up front in a "doghouse" between the driver and passengers seats.  For some people the engine noise and heat can be a problem.  You can buy fuel for gasoline vehicles at any gas station, although you sometimes have to look for one with adequate lateral and overhead clearance to accommodate an RV.  Surprisingly enough, many motorhomes run on regular unleaded gasoline but some require more expensive premium fuel.  Be sure to know what your vehicle requires.  If you use a low or mid grade fuel and the engine starts to"ping", upgrade to premium fuel soon, before permanent engine damage can occur.  One cause of pinging is pre-ignition, which means the fuel mixture ignites before the spark plug fires.  This can burn valves, which leads to poor performance and reduced mileage and are expensive to repair.  Gasoline powered vehicles will be subject to annual emissions inspections when the vehicle is registered where such inspections are required.  A poorly tuned engine also creates high levels of pollution (NOX and unburned hydrocarbons) that are really bad for air quality.

Vehicles equipped with diesel engines are more expensive to purchase but the usually deliver better fuel economy, higher torque, and longer life than gasoline engines.   The higher torque of diesels usually means greater load capacity but they may be a bit slower to get going.   Diesel engines are usually more expensive to work on.  Simple oil changes can run $200-$400!  The increased price means it may take a lot of driving to recoup the additional cost in fuel savings or longevity.  If you plan to full time and/or put a lot of miles on your vehicle, a diesel may be advantageous.  At one time diesel fuel was cheaper than gasoline, and that coupled with better fuel economy, reduced fuel costs.  But these days diesel tends to higher than premium gasoline (at least where I live),which doesn't make a lot sense because diesel is made from the dregs left over from refining gasoline.  If you do a lot of boondocking for OHV activities, you may have to carry some extra diesel fuel since the gasoline for your toys is not compatible with diesel engines.  Diesel engines in general are a bit noisier than gasoline engines, not necessarily in the exhaust system, but from direct sounds generated within the engine.  They do not have spark plugs to ignite the fuel.  The fuel is ignited by heat generated from compression.  This can sometimes be heard as a sort of knocking sound, which some people find objectionable.  Some people don't like the smell of diesel exhaust either.  Diesel chassis often have the engine in the rear (known as a "diesel pusher").  On large motorhomes this puts the engine up to 40 feet behind the driver, greatly masking any engine noise.  Finding diesel fuel on the road used to mean looking for truck stops, but the proliferation of gasoline powered automobiles has made diesel much more available.  Yet even today, not all gas stations carry diesel, so you need to check the signs before you pull in.  Make sure you use only the designated diesel pump.  Putting gasoline into your diesel vehicle will cause a lot of problems and can be expensive to remedy.  Motorhomes with diesel engines may have diesel or propane powered generators.  If your camping style is such that you use a lot or propane, you may want to make sure the generator is diesel powered to conserve propane for other uses or carry extra propane.  In some areas subject to emissions inspections, diesel powered vehicles are exempt from emissions inspections.  They will still be required to pass any required safety inspections.  But increasing pressure on air quality is forcing some areas to impose emissions controls on diesels so be sure you know what is required where you will register you vehicle.  Diesel powered vehicles often have higher weight carrying and towing capacities than their gasoline counterparts.  So if having a really big motorhome or being able to tow a really large trailer is important to you, you may want to seriously consider getting a diesel.  Be sure to check the horsepower and torque ratings  and Gross Combined Vehicle Weight Rating so you can be certain you're getting enough power for satisfactory performance.   All diesels are not alike.  You might be disappointed with the performance of some of the older, smaller diesel engines.

I have owned both gasoline and diesel powered motorhomes and found both to be satisfactory.  I've never full timed or taken long cross-country trips more than a couple thousand miles, so I was never able to take full advantage of the higher fuel economy attributed to diesel vehicles.  My diesel was a 40' pusher, and, due to its size, age, and weight, did not deliver particularly good mpg numbers.  Unfortunately, I also saw diesel fuel climb from cheaper than unleaded regular to more expensive than premium gasoline which quickly negated the cost savings I anticipated when I bought it.  More recently, diesel dropped below regular unleaded again, then bounced back higher than premium so you may have to keep any eye on prices and trends before you make any decision -- and then be prepared for it to flip back and forth over time.

The bottom line:  choose what is right for you each time you make a purchase.   As for me, there are a lot of other key factors that have far more influence on my decision than the type of fuel a vehicle uses.

Choose the right fuel.