Dealer put synthetic oil in with last oil change - is this ok and why?

Lovely.... I didn't ask for it. Can anyone recommend WHEN I should use a synthetic oil? I do mainly highway driving. Generally put about 12 -

Curious - is your comment about being wary of using synthetic at 75K if my care never had it before based on the theory that in some cases, synthetic oil has a tendency to leak out of an engine with a lot of miles that's had "regular" oil all the time? I've read that synthetic particles are so small (hence less friction) that they can leak into places "regular" oil can't.

I d>You can find endless posts of synthetic vs. non-synthetic post via

You might not have much of a choice. Some manufacturers recommend that once you put in synthetic, you should not switch back to regular (lengthy link follows).

To ismlv,

First, like a previous poster said , I am wary. I'm wary of lots of things, but in the specific case of synthetic vs. dinosaur oil, nope! I've switched for a couple of oil changes on more than one car with over 75K miles. I've NEVER had a problem that resulted from that switch.

Second, I read the note from Toyota offered by another poster.

In that post, I do NOT see where Toyota warns against switching back to dino oil. (I DO see where they do not recommend switching "back and forth", but that seems reasonable. Pick one and then dance with the one what brung you. Switching back and forth can be confusing, if not dangerous in many areas of life. :-) Fun, maybe, but dangerous. Driving is not an area where I want to live dangerously.

I suggest you NOT WORRY about the synthetic oil. I have done it with no harm. If it works for you, if you like it, stay with it, so long as it meets your auto manual's specs for oil. If you don't like it, switch back to dinosaur oil. Enjoy the car and don't worry.

If you've gotta worry, try 'piston slap' or something like that.

The above are my personal opinions only. Obviously, YMMV.

No, it isn't. I use synthetic in my Subaru; it helps if you tend to keep cars nearly forever (like I do) or do a lot of stop-and-go driving (I do). But it is NOT standard for any Subarus I know about (might be for the really high-performance cars).

I would ask for a refund on the grounds that your manual does not recommend synthetic, you did not request it, and the dealer didn't notify you in advance that they used it by default.

Get they synth mix. Get a bonus with the synthetic. Sting Rays now come with synthetic from the factory. Audi does too. Older cars. ('93) may not have the seals that work well with synthetic oils. Change it back if you have the time to get it changed every 3K.

Yes. I don't know if it's ever been proven though.

Later synth has seal conditioners the early stuff didn't; to keep really old crusty seals which would get cleaned of gunk from leaking.

Basically, don't worry.

TBerk