logevity of synthetics?

[RiceCooker]

With natural oil, it's rule-of-thumb to change it every 3k miles. How often should pure synthetic be changed? How often should natural/syn blend be change?

[Skullcamaro]

Supposedly from what I know, and correct me if I'm wrong because I might be, but synthetics should allow an extra 3,000 to 5,000 miles without a necessary oil change. I may not be totally correct. I personally change mine between 3,000 and 5,000 miles and I use full syn. oil/lubricatants.

[Dominic]

Some people go as long as 12,000 miles between oil changes on synthetics without a problem. If I can afford it though, I go 3,000 and know I'm always running clean fresh oil in my engine. If i ever had to go longer, I could, and thats fine with me =)

[DominusEtDeusNatus]

Synthetic will break down at 100,000 miles.

[BillyCobin]

That is what your oil is rated to, but I think that there are other things to consider besides the oil. One would be the filter, how long is that good for? Just because you bought the Extra Duty one or whatever just means that there is more filter elements packed inside. I would think that if you ran it for 10,000 miles on one filter that already had a lot of **** packed in (filter element) that it would end up pretty clogged.

Plus its not always the number of miles, but the type of miles. Highway, of course, are easier on the oil than stop and go.

Personally I wouldn't run it past 5,000 miles. Just an opinion though.

[DominusEtDeusNatus]

He basically hit it on the head. You guys are missing the major point. Who cares if the oil is synthetic or superduper synthetic and when it breaks down? The most important thing is the additive package(how well it lubricated and protects.) Dirt will get into the engine. It is important to change your air filter at regular intervals. Oil filter can only hold as much.

[Gregg Thompson]

Yes, dirt is the key element here. I drive 12K a year and chnage my Synthetic oil every 6000 miles or twice a year. I allow for more miles but only because its all highway and looks very clean at 5000 and so on. The oil may not break down but it will get dirty.

[Guardsman]

When I started using Redline, their tech guy told me that for freeway driving, I could go to 18,000 miles between complete oil changes, and change the filter (including a fresh quart of oil) every 6,000 miles. That was on my 3.4, with the 3.8, I'm doing 15,000 miles, and changing the filter every 5,000 miles, because the 3.8 seems to be a bit tighter built than the 3.4 was.
I can tell you that after 18,000 miles on the 3.4, the Redline oil still sticks to the oil drain pan, as opposed to regular oil, wheich just ran off like water after 6,000 miles.

[Steve Caroccia]

Old school Mobil 1 was oil change every 7-8,000 and filter change every 3500-4000 miles. The guys in the Paulsboro, NJ labs (where the 1,000,000 mile cars were tested) would say longer.