Can Someone Explain To Me Engine Oil?

[terpkristin]

I just got my first oil change in my car, and I realized that I know absolutely nothing about engine oil.

My manual that came with my car recommends 5W-20 oil for my car, though most places it seems put in 5W-30 when they change it. I did some googling and found that 5W-20 means that at 0 (I think?) the oil has a viscosity of a 5 weight oil, and at 100 deg F, it has a viscosity of a 20 weight oil? But what does that really mean, for performance? And what kind of "change" should be expected if I use 5W-30 instead of 5W-20?

Something else on Google said that car manufacturers are recommending 5W-20 to make their gas mileage ratings go up a little or something like that. But the way the article presented it, it sounded like it was a sort of a new thing to do and "well, some cars with 5W-20 are now going over 100k miles, so it can't be all bad" (or something similar to that)...

Finally, when I go get my oil changed, should I be getting a synthetic, a synthetic blend, or does it matter?

Any thoughts? Can somebody explain it to a car dummy like me?

Thanks!
/tk

[Buccaneer]

No it doesn't really matter. It used to be that you would choose thinner oil in winter and thicker in summer but those were for older cars. With newer models, it really doesn't matter anymore unless you are into fine-tuning engine performance.

[MikeVic]

You can run longer on synthetic. And even though I have a newer car, I still try to use 5W-30 in the summer and 10W-30 in the winter.

[Surtt]

Rule of thumb,

The lower number is for winter driving. It tells how cold the oil can get and stay liquid. The lower the better.

The upper number is for summer driving. the higher the number the more heat it takes to break down the oil. In hot weather the higher the better.

[Ryan S]

I use 0w-40 synthetic oil. It is pretty expensive, but I buy oil from Costco which saves me around 50% over retail prices.

[M GO BLUE!!!]

Ok, we have definite confirmation that you are in fact a girl. :D

Engine oil is like KY for the rods and stuff in the engine. Like KY, it does not last forever and needs reapplication after a time.

Don't go by what the car manual says... they want you to buy more cars! Get the oil changed at least 50% sooner than they tell you to. When I had a car I used synthetic and changed it every 3000-4000 miles, regular oil every 2000-2500.

Considering you are getting the oil changed and not doing it yourself, go with regular oil, as many shops see a woman and figure her for an easy mark. Many shops have gotten in trouble for using regular oil when charging for synthetic, and they'll rip off a man in a second, a woman even faster.

I am a sexist pig, but read past all that! :D