I just took my is250 for an oil change yesterday. The owner manual says this car requires 5W-30. However, when I went to a local store and I told the mechanic to use 5W-10 by mistake.

After I found I made a mistake this morning, I checked on the web. It seems there is no such 5W-10 oil on the market. Or at least it's not a common grade. But the recipt from the local store clearly indicated the oil they used was 5W-10. I am very confused now.

So, my first question is....Does 5W-10 exist on the market?
Then, my second question is.....If 5W-10 exist, would it hurt my IS250 for next 5000 mile oil change interval?

Thankzzzz

 

I can't recall that I've ever seen a 5w10 oil, but if the guy you brought it to actually used that, I'd get it changed again asap. Why not just call the guy and ask him exactly what he put in the car?

 

The latest TSB from Lexus recommends 5w20 by the way.

 

I can't find a 5w-10 engine oil anywhere (lots of references for motorcycle fork oil though.) There are a few references to it on some forums, but none of the usual suspects are marketing a 5w-10.

I'd ask for details about what they actually put in there. It sounds like they're not telling the whole story. If it really is 5w-10, I would drain it for sure. That's too light.

 

Also, check the sticker (if they put one on). The receipt may just be what he typed when you requested it.

 

This is why I would never pay extra to have a dealer use synthetic, how do you really know what they put in there?

 

I don't trust them even when I provide the oil. I brought 6 quarts of Red Line for my Supra to Toyota thinking it would be all good. By my usual 10k mile change interval there was a marked increase in varnish I have never seen before (or since) with Red Line. Methinks they did the old switcheroo. I've never been back to them.

 

No such thing available for vehicle use as 5W-10.
Would make no sence as the numbers are too close together to make such a oil. Must have just made a writting error.

 

May be that guy was using 10w30?

 

Can any expert decode 5W-10, 5W-30, and 10W-30 for me?

I am thinking 5W oil should be thinner than 10W. But what about the numbers in the back?

 

For multi-weight oil like you mentioned, the first number is the "cold" viscosity and the second number is the "operating" viscosity.

 

The above is correct, but over-simplified. Why don't you search the internet for information on it. Or, start here:
http://auto.howstuffworks.com/question164.htm