Synthetic Oil Change frequency?

I have a 2004 Saab 9-5 Aero turbo sedan with 64,000 miles on it. It runs on synthetic oil with a change frequency recommended by Saab of every 15,000 miles. I know that Tom and Ray recommend changing standard oil every 5,000 miles, but what about synthetics? They are supposed to resist breakdown for a lot longer. What has your experience been?

I use synthetic, but don’t even think about trying to stretch to 15,000 miles. I change out between 7,500 and 8,000. Typically I get 6 months between oil changes. Twice a year is the most I want to go.

Also, turbos like clean oil. Synthetics hold their lubricating properties longer than dino oils, but will also hold more contaminants and dirt. Changing out oil in a turbo engine should be MORE frequent than a non-turbo engine. Synthetics tend to hold up better under the heat and stress caused by the turbo. But, dirty oil causes accelerated bearing wear within the turbo. I’d cut the change interval in half just to keep the turbo happy.

Change it when the oil becomes black (the filter is no longer removing carbon).


Do NOT wait until the oil becomes black…that is NOT a good indicator of when the oil is no longer doing it’s job. I can show you oil that was only in the engine for 500 miles and is all black…I can also show you oil that is black as coal, but still is doing a great job lubricating.

With a turbo you need synthetic for long life. I would cut the drain interval in half (7500) at least. Your car has an expensive engine, and oil is cheap; 15,000 is way too long unless you only drive cross country at moderate speeds.

For most driving I would go with Tom & Ray and drain every 5000 miles.

Thanks, everyone who replied! I will cut my intervals for oil change down to 7500 miles. Great feedback.

Much depends on what type of driving you do. If your driving consists of mostly stop and go, short hop trips then every 3k-3500 miles is a good idea; and especially so considering the car is turbocharged.

Even the finest oils do not prevent the major source of contamination with short hop driving and that is moisture accumulation, etc. It’s not simply a matter of the oil breaking down.

The main reason behind oil sludging and turbocharger failures is failure to change the oil frequently and somewhere in SAAB’s recommendation is likely a “severe service” comment.

When In Doubt, Drain It Out!

Definitely synthetic, 7,500 is good or 5,000 miles is even better.

Have you noticed the price of dinosaur oil continues rising and synthetic is still sinking?
When will the prices cross?

Change it when the oil becomes black (the filter is no longer removing carbon).

I love that one.  I drive a diesel and the oil is black as soon as you restart the engine.  :-) 

Franly the color of the oil is almost totally worthless as a signal for changing it.

Actually, synthetic is also rising, just not as fast. When I was buying oil 3 years ago, synthetic was nearly 3 times as much as dino oil. Now, synthetic is less than double. I doubt they will ever cross, but the difference is definitely getting better.

Maybe Not All Synthetics Are Dropping In Price, However The Type Of Mobil-1 I Buy In 5-Quart Bottles Has Reduced Twice In The Past Year, In My Locale.


What kind of driving do you do. Eg, (country, city, highway with %). Also what is the amount of miles/month.

If you were driving 15k in 3-6 months mostly highway/country I would not hesitate to do 15k changes.

(the filter is no longer removing carbon)

Carbon is an Atom…The BEST filter available can only filter down to three microns…which is more then 1,000,000 times bigger then a carbon Atom.

Flame me if you must, but I’ve been using synthetics since the 70’s, with 15k intervals (a few over 20k), with not a sign of any dificulties. Some folks do this. It might not be wise if you’re in warantee though.

But, you don’t drive a turbo car, do you? That is one of the special criteria of the OP’s question.

Agreed…I wouldn’t do it with a turbo.