To Yahtec:
There are a bunch of "old mechanics tales" about synthetic oil. Most came from the fact that when Synthetic came onto the scene about WWII, most oils had a lot of Parafin in them and did NOT have any detergent to keep engines clean. Old style leather and cloth seals needed the accumulated parafin and dirt to "plug up" the seal and prevent big leaks. Putting detergent oil in these cars of ANY type, regular or synthetic caused big leaks. Since Synthetic was new, it got the undeserved rep of causing leaks. Since it didn't break down and turn to sludge or run like molassis when cold, it also was thought to be "thin and runny" and prone to leaking more than regular oil.
Truth is that ALL oils in cars today are detergent, and all oils that meet the various specifications can be interchanged or even mixed with no bad results. It is best to stay within the range of weight specified by the manufacturer or rebuilder. Synthetic also will retain it's specified weight range better than regular oil so it is LESS likely to leak or burn through than regular oil.
You CAN switch to synthetic at any point in an engines life. You can switch back to regular. There will be no bad effects either way.
So why do some people still insist that they get more oil use/leaks with synthetics? (and some will post so here you can bet). Basically it is because engines sometimes use more oil due to weather, driving style than due to what oil you run. I can site cases of LESS oil use/leaks with synthetic for every case of increased use. Sometimes you get what you expect. Someone will "try" synthetic, but they are not a believer. So they get what they expect, more oil use because the monitor the situation better than before. There is no valid proof that synthetic by itself will leak or get burned up more than regular oil, in fact, quite the opposite.
Most high end NEW cars get synthetic from the first turn at the factory so there goes another "old mechanics tale" that cars won't break in properly with synthetic. Bunk, you can run synthetic from brand new.
We DO have much proof from every authoritative source that using quality synthetic will reduce wear and tear, and increase gas mileage (slightly, not talking a miracle here).
Finally, about extended drain intervals. With a synthetic designed for extended drain intervals, you can extend to 25,000 miles or more between changes. This isn't pie in the sky, I have done it many times, and truckers do it all the time. Porsche recommends extended drain intervals from new, and most new cars that have an oil change monitor through the computer will let you go 7000+ miles easily if you drive some on the highway (stop and go short trips are the hardest on oil and the engine). If in doubt, follow your manufacturers recommendations, but especially when out of warranty, you can extend drain intervals, and save money, help the environment and more.
Don
