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Oil type

Is conventional oil or synthetic oil better for my car? 2002 Outback 98,000 miles.

I have used both in my Subaru and don’t really see a difference. I run 5K mi conventional and 7.5K when I put in synthetic. I have noticed a slight increase in oil consumption at 6-7.5K miles, so I tend to stick with conventional and go the 5K mi.

See the synthetic oil discussion under General Discussion tab.

If the owner's manual does not recommend or specify synthetic then either should be fine.  Synthetic has some benefits even if not not specifically recommended.  You likely will get a little (may be too small to notice) mileage increase with synthetic and you may be able to extend oil changes.  But don't go beyond the miles recommended in your owner's manual.

We have had this question many times on this forum and there is no clear winner. Most engines were designed to run on conventional oil and they do just fine. There appear to be no significant advantages to synthetic oil, but some car owners choose to baby their engines with the expensive stuff anyway.

A few luxury cars specify synthetic oil, so owners should follow that advice. You can take your pick.

At 98k miles I would stay with conventional. You may start using oil if you switch now.

Read the owners’ manual and use what they recommend.

Manufacturers will generally recommend synthetic for engines that subject the oil to extreme conditions, like those with turbochargers. The guys that wrote the manual are the true experts.

I think it is pretty clear that synthetic oil is superior, what is in controversy is if the synthetic earns its much higher cost. Some see it as a 300% premium for a 30% increase in performance. Others want the best at any cost.

I’m not a mechanic or expert by any means, but I believe that if you change your oil within the mileage or time recommended by your vehicle’s manufacturer - unless synthetic oil is specified - using synthetic oil will not have any added benefit for vehicles that don’t require it.

Synthetic oil has no real advantage under most conditions. If you live in a place where the temperature hits 20 below 0, or if you go on the Autobahn and run your car at top speed, then synthetic is good. I’ve known people to run cars nearly 400,000 miles on conventional oil, and the rest of the car will usually fall apart before the engine does.

Are you guys saying synthetic oil is NOT less subject to sludging than dino oil, on those engines which have sludging problems?

A lot of oil experts on various URL’s have said over the years that one should use synthetic for maximum resistance to sludging.

I pay less than $30 for Mobil-1 EP 5 quarts at Wal-mart. I have told about testing my oil, and for my driving pattern, it is good till 10,000 miles, so now I change at 8,000 miles. (Warranty is long expired.) I would never drive dino oil that far, and I bet most of you wouldn’t either.

Frankly, I do not buy your statements that synthetic serves no purpose at all on cars where it is not recommended.

Think about what you are saying. Some cars recommend synthetic oil for normal driving. Why on earth would they recommend synthetic if there is no benefit from it in normal driving?