Went with GF to get her oil changed since she knows less than me about cars, didn't even know her Si was FWD :O

Anyway, we get there and pull into the bay and there is a whole bunch of oil on shelves and stuff to choose. I pick up a bottle of Mobil 5W-30 full synth and say something like this is the oil we need. Go inside wait for car. After leaving I look at receipt and it says Castrol 5W-20 synth. I'm pissed but didn't go back because there is no way to prove I asked for the other oil. Anyway, how bad is it to use the wrong oil?

 

5w-20 wont hurt it a bit. She'll get better gas mileage and it'll burn a little faster, but other than that she'll be fine. Honda actually specs 5w-20 on their engines now for better gas mileage, including your '03.

 

What year Si (Civic??) is her car? Maybe 5w-20 is the correct weight after all.

 

Something tells me that since Honda "switched" to recommending 5W-20 it encompasses their whole line from 2003 on.

 

Is it safe to use 5w-20 for over 150K miles?

I use 10w-30 in the summer & 5w-30 in the winter....

 

I just looked... 2007 Civic Si calls for 5w-30, not 5w-20.
Still, not really too bad. If she's planning to take it to the track, then change it first.

No. I wouldn't use ANY oil for an interval of 150k miles...

 

I think he meant was it safe to use in a car that has over 150,000 not use the oil for that long

 

hahaha
I'm not quite sure to use a lower viscosity
Since my engine is old I don't think its good to use synthetic since the oil is much thinner than conventional & wouldn't lubricate well....
Don't know if I phrase that right....

 

lol silly rabbit

 

Yeah, I was just being a wise-@$$

It's not the mileage, it depends on the condition of the engine. We still don't know what year Civic Si, but it probably calls for 5w-30. That's what you should use. But don't panic about the 5w-20 unless she takes the car racing.

Besides, the 5w-20 might be a mistake on the reciept while the actual oil is 5w-30.