I know there are a few good mechanics on here, and I can think of few groups I trust more than Dopers. So, Doper mechanics, are synthetic oils worth the cost? I have to do an oil change within 400 miles, and I’m wondering if I need to switch.
We bought the car in question, a 2005 Saturn VUE, last October. It has ~70k miles on it now, and we just returned from a long road trip. I got the oil changed mid-trip, but have put another 2600 miles on the car in the past three weeks. The last oil change (and all previous, that I know of) were with conventional oil. It has a 3.5L V6, although I’m not sure that the engine type really matters. We have a 55-mile round-trip commute 5 days per week, so the car gets quite a bit of mileage on it.
The board mechanics will be by eventually to comment, but at first glance I have to ask: Why are you changing your oil every 3,000 miles, especially if most of those are highway cruising miles? According to the owner’s manual (PDF), the VUE is equipped with an engine oil life monitoring system, like other GM cars, that will tell you when you need to change the oil.
Whether or not you should switch to synthetic is a question I’ll leave to the mechanics.
I agree with SanibelMan: changing the oil every 3K miles is a waste of oil and money, especially since most of your driving is long distances between cold starts (cold starts are hard on the oil). Your manual probably specifies 6,000, maybe even 7500 miles between changes. The manufacturer would not specify such an interval without being confident that there is large margin of safety - that is to say, your oil could probably go significantly farther than 7500 miles (or whatever the owner’s manual says) before you’re in danger of compromising engine life. Save money, save oil: extend your change interval to whatever the manual tells you.
Synthetics do offer somewhat better lubrication and significantly better tolerance of high temperatures. there are applications where you might see a benefit from this, but commuting in your Saturn is probably not one of them. Unless you’re spending a lot of time at wide-open throttle and high RPM’s (track day?), non-synth oils will probably get your Saturn’s engine to 200,000+ miles without incident.
I’m with the guys wondering about the 3K oil change schedule, my RS6 does 5K miles (depending on usage) between oil changes. Synthetic/non-synthetic oil shouldn’t be an issue with your type of vehicle, and usage; neither should cause problems. Hopefully a mechanic wonders in with vehicle specific recommendations.
Synthetic worth the additional expense? For your situation, probably not.
To really know if your oil should be changed, you’d have to have it analyzed by a lab. But since that costs more than changing the oil, we instead go by best estimate based on the info we have. The standard calculation is the 3000 miles for severe service/7500 for normal service listed in your Saturn’s maintenance schedule. As you can imagine, that’s a rather crude estimate, partly based on a number of assumptions. A significantly more sophisticated estimate is derived from your car’s oil life monitor system, which has specific info about how your engine has been run. Your best bet is to go by it (make sure you or the shop resets it at each oil change).
Continuing to be vigilant about oil changes will do you far more good than switching to synthetic oil. As long as you’re using good quality oil, the intervals shown by the oil life monitor system should be quite adequate.