5W-30 instead of 10W-30?

I was reading an article about how to slightly increase your gas
mileage. One thing that it said was to make sure you use the proper oil
for your engine. The '90 Celica I have is recommended to use 5W-30 oil
but since I have had it, I have always filled it with 10W-30. I
remember having other vehicles in the past where 5W-30 was recommended
but 10W-30 was used.

Should I be using 5W-30 and not 10W-30? If I switched to the "correct"
oil, is it possible that I would notice some slight improvement?

Thanks!

J wrote:
[color=blue]
> for your engine. The '90 Celica I have is recommended to use 5W-30 oil
> but since I have had it, I have always filled it with 10W-30. I
> remember having other vehicles in the past where 5W-30 was recommended
> but 10W-30 was used.[/color]

If the numbers mean what they say, you should only notice a performance
difference inside the small window while your vehicle is coming to
operating temperature. At nominal crankcase temp, both are a 30wt oil.
I doubt you would notice the difference at the pump.

However, if you're in an area where the temperatures get low in the
winter, you should probably be using the 5w30 anyway.

"J" <omnineko@yahoo.com> wrote in message
news:1162091356.980815.66240@e3g2000cwe.googlegroups.com...[color=blue]
>I was reading an article about how to slightly increase your gas
> mileage. One thing that it said was to make sure you use the proper oil
> for your engine. The '90 Celica I have is recommended to use 5W-30 oil
> but since I have had it, I have always filled it with 10W-30. I
> remember having other vehicles in the past where 5W-30 was recommended
> but 10W-30 was used.
>
> Should I be using 5W-30 and not 10W-30? If I switched to the "correct"
> oil, is it possible that I would notice some slight improvement?
>
> Thanks!
>[/color]

You should use the weight and grade of oil that is recommended by the
automaker. It is possible, though not very likely, that you would notice
some slight improvement in fuel economy by using 5W-30 instead of 10W-30.
5W-30 offers better lubrication when first starting the engine than 10W-30,
so bottom line, stick to the automaker's recommendations.
--

Ray O
(correct punctuation to reply)

On a 17 year old car with normal mileage - I'd stick with the 10W30 --- even
10w40 in hot summer months if in southern states..

"J" <omnineko@yahoo.com> wrote in message
news:1162091356.980815.66240@e3g2000cwe.googlegroups.com...[color=blue]
>I was reading an article about how to slightly increase your gas
> mileage. One thing that it said was to make sure you use the proper oil
> for your engine. The '90 Celica I have is recommended to use 5W-30 oil
> but since I have had it, I have always filled it with 10W-30. I
> remember having other vehicles in the past where 5W-30 was recommended
> but 10W-30 was used.
>
> Should I be using 5W-30 and not 10W-30? If I switched to the "correct"
> oil, is it possible that I would notice some slight improvement?
>
> Thanks!
>[/color]