Suggestion when getting any new or even used LD RV... May 28, 2009, 01:23:41 pm Yahoo Message Number: 102656Back when Mobil #1 Synthetic Oil was introduced, I wrote the company and asked for any test results they had showing their superiority claims on Synthetic Oil vs. Petroleum Based Oils. What they sent to me blew me away and I have been using Mobil #1 Synthetic Oil in every vehicle, RV, boat or whatever since... To the best of my memory, here is what they did. They took two brand new Lincoln Continentals, one they ran on conventional petroleum based oil, the other on Mobil #1. They ran both vehicles to 100,000 miles, changing the convention oil as recommended, and the Mobil #1 at 10,000, they changed the filter and added only 1 qt to replace what was lost due to the filter change, and would change the oil and the filter at 25,000 miles. At the end of the test, they broke down each engine and micrometered them, the Lincoln that ran conventional oil had sludge build up under the valve covers and was burning some oil. The Lincoln using Mobil #1 was within Factory Tolerances to have left the factory as a New Engine, was not burning oil and had zero sludge under the valve covers or anywhere else for that matter. I have been a loyal user with their product ever since believing that since they created the Synthetic Oil industry, they have the most experience. In fact, to this day, the majority of race teams still use Mobil #1 Synthetic Oil in their race cars. I figure it is worth the extra cost of their oil and their special Mobil #1 Oil Filter to get almost frictionless results in your engine as a result.Ed Klaus