Cadillac Repair: Oil Change/Timing Chain, oil change interval, oil change intervals

Question
Hi Bill,
Own 1989 Chevrolet Astro,4.3 liter-V6,156,000 mi.,runs good, never valve cover leaks. Use Castrol "High Mileage,10W40". Change every 3000-3500 mi. One mechanic said 3000 mi. oil change too often; says companys trying to sell more oil. Gets dark caramel look around 3000 mi. Should I change then, even if 3000 mi. oil change  too soon? Is it better to go by color of oil, and not mileage?
My timing chain is at 116,000 mi. When should I change? Not making any noise-doesn't run rough.

Thanks!

Mike E.

Answer
Hi Mike, Just to follow up on the oil change interval question. I had the oppertunity to read an artical in a magazine called "Oils and Lubes" from around 11/04. In it there was an article about oil change intervals but the interesting thing is that in Europe where this comes from there aren't any quick lubes that you can just pull in and get a change. The vehicle owner has to schedule an oil change appointment with a shop and can expect to wait up to 4 hours to get the change with the price around $100. However what they do is a comprehesive inspection of the cars overall mechanical road worthyness along with the change. Also the oil is specially formulated to last between 20-25,000 miles and can cost up to $20 dollars a quart. They do have Mobil 1 but there are clasifications of oil that excede or are better that Mobil 1 over there. So in answer to you previous question, if you use Mobile 1 or oil that is formulated to a better clasification then running you oil for a year or longer with just topping the oil off if it gets low will not do any harm to youe engine and you will save on the cost of oil changes. If the oil you use is substandard and the chemicals break down/wear out before a years time then engine damage will occur. The oil itself just gets dirty but its the chemical additives that wear out. Kinda like doing the dishes. You still have water in the sink but the effectiveness of the soap is lessened the more dishes that are washed. At the time the article was written the Europeans were changing oil every year and a half and hopeing to get 2 years out of their oil. As of now the american manufacturers with the exception of Mobil 1 don't even compair in oil quality but in Europe there are oils made to higher standard than in North Americas Mobil 1. Just thought you might like to know. Bill