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Q. What's the story on synthetic engine oils and do you recommend them?
A. 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 thesetemperatures. 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.
Q. 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?
A. 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.
Q. Should I be concerned about using low sulfur diesel fuel and should I use a fuel additive to handle this fuel?
A. 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.