Good Sam Camping Blog
TEST Header
Filed under: Navigator, RV Maintenance

Mark, My Words: Q & A with Mark Nemeth – April 2013

April 24, 2013 by · Leave a Comment 


Hi, folks. I’ll cover some common RVing questions this month and share some tips on window and roof sealing. I hope you are enjoying the spring weather! Remember to submit your RV questions to!


Would you know where we can get a list of makes of vehicles that are safe to tow without having to use a dolly? Thanks, Joan

Hi, Joan:

There is a comprehensive list of vehicles that can be towed 4-down (without modifications) available at Motorhome magazine’s website. See   and click on “Resources” / “Dinghy Guides.”

Many vehicles with automatic transmissions can be towed this way without modification, and most are supported by at least one tow bar manufacturer for baseplates and adapters. Also, vehicles that are not listed as towable-4-down can often be modified with either a transmission lube pump or a driveshaft disconnect. Remco makes lube pumps for most vehicles, and their website is at, or you can call them at 800-228-2481 for more information. Driveshaft disconnects are available through SuperFlow, who purchased the driveshaft division of Remco a few years ago. Their site is, and their number is 855-447-3626.

In all cases, be sure to double-check with the vehicle manufacturer for the final word on tow restrictions before deciding on a particular model. Most models that can be towed 4-down will have specific instructions in the owner’s manual that you must follow to prep the vehicle for towing.


Hi, Mark,

First-time class-A shopper, 40-foot range.  I notice that most all are diesel.  I think I “get” the advantages of torque and engine life, but diesel prices are so inflated, I really hate to be taken advantage of.  How different is the mpg?  Your thoughts, please. Thanks, Don

Hi, Don,

When we are talking about vehicles pulling trailers or 5th-wheels or smaller motorhomes, you will usually have a choice of gas or diesel engines. On these kinds of RVs, in my opinion, there are some definite advantages to gas engines. In the “olden days,” diesel engines offered better fuel economy, longer-lasting engines, more torque, and diesel fuel was cheaper than gas. Today, with the advances in gasoline engine technology, the increase in diesel emissions regulations, and the fact that diesel fuel is now more expensive than gas, the playing field has leveled a lot. However, when we start getting into larger motorhomes with gross vehicle weights of 30,000 lb. or greater, the diesel engine offers significant advantages. Most of these large diesel motorhomes are built on heavy-duty bus or custom chassis and utilize modern diesel engines and Allison transmissions. Diesel engines specialize in torque, and that’s what you need with a heavy vehicle like that. There are very few gasoline engine large coaches out there once you get into that 40-foot motorhome category. Most gassers will be built on a truck chassis, and the negative difference in ride quality and handling will be noticeable. If you are towing a heavy vehicle or trailer, or plan to drive into the mountains, the diesel coaches will be better able to handle the additional strain. Fuel mileage on most large coaches is pretty consistent and depends a lot on how you drive them. Most folks get somewhere in the 6-8 MPG range with a big diesel and a bit less with a gas coach. There are happy gas motorhome owners out there who would disagree with me, but I think that, if you are shopping for a 40-foot motorhome, you are most likely going to be happiest with a diesel.


Hello, Mark,

Can you advise what you think of running your RV fridge on an inverter (120 volts) while on long trips? Is it better than running it on propane while in motion? We’re going on a longer trip for many weeks and wonder what the best way to keep the fridge cool is?

Thanks, Colin

Hi, Colin,

Whether to travel with the refrigerator on or off is a choice that all RVers must make. On one hand, running the fridge on propane while traveling does present a safety hazard, in that an open flame is present, and the propane gas supply must be turned on at the tank. On the other hand, many RVers travel this way and never have any problems. Personally, I prefer to travel with the propane shut off at the tank. That way, in case of an accident, there is less of a chance of damaged piping allowing propane gas to escape and cause a fire. Most RV refrigerators will keep food cold for 6-8 hours when turned off. When I was traveling with my 5th-wheel, I found that even on the hottest days my food did just fine with the fridge off. (It really helps if you don’t open the door a lot!) Some folk will freeze blue ice packs the night before and then place them in the fridge while traveling with the fridge off to help keep everything cold. Now that I have a motorhome, I use my inverter to run the fridge on electric while traveling. This is the best of both worlds as I can have the propane turned off and still run the fridge. Another option for motorhomes is to run the generator while traveling. This is a bit of overkill to just run the fridge, but if you like to operate a roof air to keep the rig cool on hot days, an added bonus is that you can also keep the fridge running. Most inverters will draw 25A to 50A of DC current to operate the fridge. Larger 4-door units may exceed 70A! This is why it’s a good idea to only run the fridge on the inverter while the motorhome engine is running! Unfortunately, what is good for motorhomes doesn’t work so well with a travel trailer.  While your motorhome alternator can usually keep up with the demands of your inverter running the fridge, in a trailer the charge current available from the tow vehicle alternator to most trailers is not adequate to meet the demands of the inverter. Likewise, you really wouldn’t want to run a generator in your trailer or 5th-wheel while towing. For trailers, it really boils down to running the fridge on propane or shutting it down. If you have a trailer, get a fridge thermometer and try a couple trips with the fridge off. You may discover that you don’t need to run it after all!


Hi, Mark,

My question is, can you use a 50-amp/30-amp pigtail on a motorhome that is wired for 30 amps? Many parks have 50 amps now. When the 30-amp places are full up, I need to know if I can use a 50-amp/30-amp pigtail and plug into a 50-amp box when I’m only wired for 30 amps. Lou

Hi, Lou,

If you use an adapter that is specifically designed to convert your 30A RV plug to a 50A plug, you’ll be just fine. The adapter is designed to only pass one leg of the 50A 125V circuit to your 30A power cord. Since your RV has a 30A main breaker inside the rig, it will protect your internal wiring and systems from excessive amperage. These adapters have proven to be safe and reliable and are a great addition to any RVer’s gadget box! I also carry a 30A-to-15A adapter and a 15A-to-30A adapter to cover all of the possible outlet types.



I have a question about maintenance. The sealing around the windows and door is a gooey mess.  Do I need to clean it out before I re-seal?  Or do I put new putty in over top of the old? What about caulking? Do I remove the old before I put in new?

Thanks! Patricia

Hi, Patricia,

The best way to re-seal a window is to completely remove the whole window and frame and remove all the old sealant from the rig and the window frame. Then apply new butyl rubber caulk to the outside window frame and re-install the window in the rig. Once you tighten it down, trim the excess butyl sealant away with a knife. This is far better than trying to put new sealant or caulk over the old stuff, and it will last a lot longer. The butyl rubber caulk comes in a roll and is available from most RV parts sources. Here’s an example online:

On the roof, you should inspect all of the roof seams and re-coat them every year or two or when any visible cracks are found. In most cases, you only need to remove old roof seam caulking that is not adhering well. If it is firmly attached, you can clean it with soap and water and apply a new coat of sealer right over the old stuff. Be sure to use a sealant that is designed for the type of roof you have (rubber, aluminum, fiberglass).

mark mugshot 2013

Mark Nemeth has been involved with all things RV for more than 15 years, including almost five years on the road as a full-timer. He is the RV education director for Escapees RV Club and oversees the highly acclaimed RVers’ Boot Camp and SmartWeigh programs. Do you have a question for Mark? Please submit your question via email to

Please remember, material will be edited. Because of the large volume of material and correspondence submitted, individual replies will not be possible, nor can we acknowledge receipt of your material. Selected questions will be answered in future issues of the RV Navigator newsletter in the Mark, My Words column.

Founded in 1978, the Escapees RV Club provides a total support network for RVers that includes a wide variety of opportunities for fun, adventure, and education.

MAIL SERVICE  The best mail–forwarding service in the country. Members can personalize their mail delivery receiving only the mail they want when they want. MAGAZINE  Award-winning magazine written for RVers by RVers.

CHAPTERS  There are 51 chapters across the U.S., Canada, and Mexico that offer local luncheons and rallies within 150 miles of home.

HOPs  Theme–related outings and adventures held across the country.

ESCAPADES  Five–day educational events that offer over 60 seminars and workshops to educate, entertain, and enhance the RV lifestyle.

PARKS  Our discount park system offers a variety parking options. PLUS MUCH MORE!

A complete listing of all Escapees events and a comprehensive list of member benefits are found at

Speak Your Mind

Tell us what you're thinking...
and oh, if you want a pic to show with your comment, go get a gravatar!