which oil for HOT desert driving?

<div class='quotetop'>QUOTE(desertbriez @ Aug 22 2007, 03:02 PM) [snapback]500500[/snapback]</div>

Your owner's manual must have a page for that. It should show a chart, with oil viscosity and temperature range for each viscosity.

For the climate I'm in, 5W-30 is the right choice, and I use Mobil 1 in that viscosity for my Prius. Keep in mind that you have a water-cooled engine in your Prius, so the temperature in your Prius engine won't be much higher than the engine in my Prius. We both have the same thermostat that regulates flow through the engine and radiator. Our maximum engine temperatures will be about the same, even though you are in the desert.

Good luck,

Harry

 

I'd actually like to know this too but from what I've read 5w-30 seems like the the way to go and if I'm not mistaken this is what Toyota recommends in the manual.

 

<div class='quotetop'>QUOTE(treehggr @ Aug 22 2007, 12:39 PM) [snapback]500532[/snapback]</div>

You definitely don't want to change the low-end number - that's the rating for cold weather. A 10W30 and a 5W30 probably act about the same in hot weather. On the other hand, I'm driving the specified 5W30 in Phoenix at 110o with no problems, and that's what the Toyota dealers in town use, so stick with the manufacturer's recommendation.

 

the engine runs at 180F so whats desert heat compared to that ?

I think may automakers and dealers just want you to change the oil and always buy the most expensive. I don't believe you can tell them apart in real world testing.

My old 2003 ciciv hybrid recommended 10,000 between oil changes with 0w20. I never had any problems. The dealer always said you should change at 3K. Of course more money in his pocket.