I know, I'm full of questions.
Our plan is to buy our coach at least a year before I retire, to allow for any needed repairs/upgrades. During that year we won't be using the coach much. I've read about the issue of condensation in fuel tanks, and I'm familiar with it from my flying days, so my thought is to always keep the tank full. I've also read that diesel fuel is formulated differently during cold weather than warm weather, and one should always buy the local fuel for the local conditions. What happens, though, when the coach is parked for a month or two, and the weather changes?
There are anti-gel agents that can be added to the fuel to prevent fuel coagulation during very cold weather. There are also anti fungal additives to prevent growth of unwanted specimens in the fuel tank during hot weather. As you have likely read here before you would need to exercise the coach by driving it at least 30 miles every month. This would include the generator, propane system, etc. inclusive of all coach systems, dash A/C so on and so forth.
Peter
My understanding and experience says that you should not worry much about seasonal fuel issues unless you plan to operate the coach in very cold conditions. In Missouri, I would expect you will find some moderate temperatures during every month of the year when you could exercise the coach.
We drive our coach about 11,000 miles per year. We have traveled and stayed in the coach during temperatures from 0F to 105F. We have about three years of experience in DP coaches with Cummins engines. So far we have not had any significant fuel or engine problems. Other people may have other recommendations based on their knowledge and experience.
We live in a warm climate and do not winterize our coach. I keep it plugged in and use the HVAC systems to avoid extreme temperatures inside the coach. I do keep the fuel tank full to minimize condensation, to be ready to travel, and to keep a maintain a blend of fuels. I don't use fuel additives. I try to drive our coach at least every month. If we don't take a significant trip during a month, I exercise the coach for about 20 miles at speeds of 30 to 65 mph. I operate generator, all air conditioners, windshield wipers, air horns, faucets, lights, etc.
I am with Peter on this.
When storing the coach:
Fill diesel tank to minimize condensation.
If storing over 3 months in winter or 2 months in summer, add a Biocide. Any marine store has it, as storing diesel in a boat has the same issues. Few truck stops do, as they burn their diesel very quickly.
If storing "summer grade" (aka #2 diesel) through winter, add an Anti-gel (every Walmart has it).
No big deal!
Brett
Winterized diesel is supplied to stations depending on the severity of the weather. Fuels are blended and have additives to lower the CFPP (Cold Filter Plugging Point) so when the engine is started in cold weather, the fuel has not gelled and the injectors can spray it in fine enough particles to ignite. In the past, fueling stations sold #1 diesel otherwise known as premium diesel. This is basically kerosene. Other owners have added up to 20% gasoline to keep the CFPP low. With the newer common rail, high pressure injection systems, kerosene or a diesel/gasoline mix can ruin the injectors as the very high pressure can cause the fuel to explode in the injectors. Older Bosch injection pumps produce approximately 3000 psi at the injectors. The common rail injectors see about 30,000 psi or ten times as much pressure. The high pressures and electronic controls help keep noise and emissions down while increasing fuel mileage.
The best recommendation is to either in your owner's manual or online, find out exactly what fuel is recommended for your engine. Rule of thumb is older RV engines can tolerate most any kind of diesel or even cooking oil while the new rigs are very particular in their requirements. Traveling to Mexico can be a problem in late diesel RVs where 15ppm ultra low sulphur diesel may not be available everywhere.
If you store your RV with summer fuel, its not a bad idea to include additives in the tank for cold weather starting. Never a good idea to not drive/start for months at a time.
Pierce
If your concerned about jelling fuel, you can add 10% kerosene, that will take your jelling temp way way down.
If your worried about the slimmy black gooey mess, then go with the anti fungus additives.
Best to drive it and keep fresh fuel in it.
FWIW
Dave M