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Monday, July 19, 2010

Gas vs. Diesel - Our View

Ye olde argument.  Which is better?  Ford or Chevy?  Gas or Diesel?  Toilet Seat, Up or Down?

We have owned both types of Class A motorhomes, a 2003 Winnebago Adventurer 35U on a Workhorse W-22 chassis with the 8.1 liter V-8 gasoline engine and now our current 2007 Winnebago 39K Journey on a Freightliner chassis with the Cat C-7 diesel engine.

We owned both for an extended period of time, the Adventurer we had driven over 45,000 miles before we traded it in for our Journey, which we've now driven over 30,000 miles.  A lot of miles to make an informed decision and we're not even fulltimers...yet.

So, to answer my own question, which is better?  Gas or diesel?  The way I see it...both!

I do as much of my own work as possible, most of the time the only thing that limits me is having the large tools to do certain jobs.  I don't have a nice, large garage to work in so most maintenance items are done street side or in a parking lot. 

My reason for liking the gas best is this, it costs a lot less when new to purchase.  It can be maintained easily if you have a little mechanical ability.  Supplies cost less.  Example, oil and filter change, the gas engine took 6 quarts of motor oil and a filter.  Easy to drain and refill, no problem taking the old oil for recycling.  I changed the oil every 5000 miles.  Also included was a greasing of the chassis, which usually took about one half a tube of grease.  Another item was the fuel filter, a five buck item that took all of 10 minutes to change, it was underneath the motorhome inside a frame rail.  easy to get to, easy to change.

I had the Allison transmission fluid changed by an Allison dealer, I did not have any way to pump new fluid into the transmission.

I found the gas engine had plenty of power, and I averaged about 7-8 mpg towing my Honda Element.  I drove it up and down many mountain roads out west and never found that I wished it had more power.  It drove and rode pretty well, even though it had leaf springs for suspension. 

The life expectancy of the GM 8.1 engine was estimated to be 200,000 miles before needing an overhaul or replacement.

On our Journey, the diesel chassis cost more (way more) than the Adventurer.  It has the Cat C-7 six cylinder diesel engine.  It is five feet longer than the Adventurer and is triple slides vs dual slides.  I average 7-8 mpg towing the Element.  I have driven it up and down many mountain roads out west and found it has plenty of power for me, I don't wish it had more power, but I'm not looking for a race car.  It has air suspension and air brakes which make it ride and stop very well. 

This motorhome, however, is a much more complex unit, with many more maintenance items.  It takes 19 quarts of oil, a problem to catch and recycle.  I installed a special valve in place of the oil drain plug (I'll cover this in a future post) so I can drain some of the oil into a drain pan, stop the oil draining, empty the oil drain pan into a large container, the restart the draining.  Then I can recycle the large quantity of oil.  I change the oil every 11,000 miles or annually, whichever comes first.  Along with the oil change and filter, I also change the two engine fuel filters.  At the same time I grease the chassis, using about a tube and a half of grease. (Note:  I also have to grease the universal joints and the drive shaft slip joint every 5,000 miles).  Additionally, the exhaust brake has to be lubed every six months, the engine coolant must be tested for corrosion inhibitors at the same interval.

With the air brakes, you have three tanks that need to be drained monthly, a little thing but very important.  At the three year mark, the air brake filters have to be replaced, as well as the air filter and the engine coolant.  The coolant I have to have done at a Freightliner shop because again I don't have the facility to drain and refill the large quantity of coolant.  The rear axle differential and the front wheel bearing hubs have to be drained and refilled annually, again a shop job because I have no way to pump large amounts of fluid into the differential. 

When the Cat engine hits the 35-40,000 mile mark, the valves have to be adjusted, then not again until 150,000 miles.  I'm rusty on doing this, so I'll let a Cat dealer do this.

Lastly, at the 48 month mark, the Allison transmission has to have its fluid and filters replaced, yep, another shop job.

In total, the diesel chassis costs way more to maintain than the gas chassis.  So what is the attraction?

Several, a larger motorhome to live in with much more carrying capacity (known as CCC).  Higher towing capacity, I could tow a Hummer easily (if I wanted to - NOT!).  The air suspension provides a much nicer ride and the air brakes are really good. 

Here is the reason we bought the diesel, unlike the gas engine, the diesel will go much longer before needing rebuilding.  I can count on at least 500,000 to 1 million miles of use with proper maintenance.  So I have a power plant that I'll never wear out and will have exceptional re-sale value with proper care.

So would I buy another gas powered RV?  Yep.  Marti and I have already talked about our plans for down the road, we'll use the diesel Journey until we're at the point where we choose to return to a house, then we'll sell and buy a smaller gas powered motorhome, probably a Class C, with enough room for a couple of grandkids.  We fully intend on continuing to travel, but only a month or two at a time, so we won't need to carry everything we own.

And I can change my oil in the drive way. :c)

Sorry, ladies if this was too technical, but hey, at least it's not another museum tour! ;c)

Thanks for visiting and pleas feel free to leave a comment.


  1. Great post Paul, lots of good info hidden in there. Now I just need to collate it all so that I can do all that work myself.

  2. A comment on the maintenance cost differences would be helpful and interesting. You have enough miles on both to estimate a cost per mile. I've always instinctively known that the diesel is more expensive to maintain, but have never seen actual numbers. Would you mind?

  3. Great post - I like the analysis. I'm also curious about the modified drain valve...pretty clever.
    3 more days until you have your baby back!! (Even a coastie can count that high)

  4. CWO Dahl, I ran across your blog purely by surfing and my wife who was leaning over my shoulder said, "Hey look he's a retired Coast Guard Warrant Officer!"

    I"m a retired Coast Guard Chief. Retired in 2010. Semper Paratus!

    My wife and I are considering the move to full time RV'ing and we have basically wiped out the downtown library of RV books. We're both researchers by nature, hence how I ended up on your blog.

    We were looking at Gas vs. Diesel, found your article to be very informative but I was an SKC not an MKC haha. I know that only you'll get that.

    Anyway, it is great to find another Coastie to bounce things off of. If you are on Facebook, I'd love to add you as a friend as I'm sure we may have a ton of questions and it would be great to have a fellow Guardian in our corner.

    My Facebook profile is

    Thanks for posting!

    Chief Eric Highland, USCG (Retired)

  5. your blog is wonderful. this article alone convinced me to buy both gas and smaller. i am considering buying one and renting out my home...enough to pay for both. my question that really reasonable? is living 100% on the road really a doable thing?

  6. Nice blog... Currently in April of 2014 gasoline seems to be more economical than ever with diesel going for around 60 cents more a gallon and also the DEF cost. We have a 35 ft National Sea Breeze with the V-10 and are very happy with it.

  7. In my opinion, each of those types of oil do work in their own way and has composition that will serve your RV for the long haul, albeit in all those varied terms. What is pertinent is to have access should you need them, especially when your RV breaks down, rans out of fuel or you get stuck along the way.

    Abraham Yates @ Apache Oil Company