Oil Change time - 5W-20 or 5W-30?

[dascar]

My 2004 RX8 has 36k on it and it's time for some new oil. Should I follow recommended 5W-20 per the manual or go with the slightly heavier 5W-30 since my car has a few miles and I want it to last a while and the heavier 5W-30 should give me extra protection than the thinner 20 stuff. I researched around and was surprised to find that Mazda recommends the 5W-20 oil ONLY in the USA - the rest of the world gets 5w-30. Here in Denver, summer is approaching (hot temps). I don't drive it real hard nor put on more than 200 miles a week (and most of those are to work and back - rarely over over 55mph since it's all city driving). I am savvy enough to know NOT to use the synthetic oil on these rotaries. I am slightly concerned about voiding the warranty (and/or being ineligible for a class action suit against Mazda for failed engines should one arise) by switching to the beefier oil. My car is running awesome - I want it to stay that way.

[Huzer21]

After a few Renesis rebuilds, there are a couple of shops that even recommend 10w40. I'm going with the 5w30, currently.

[Army RX8]

I run 5W20 in mine and havnt had any problems yet. If your just rollin around in it as a daily driver and she's stock I'd stick with what mazda reccomends.

[jeffms6]

<div class='quotetop'>QUOTE (Army RX8 @ Jun 30 2008, 02:08 PM) [url=index.php?act=findpost&pid=54476]<{POST_SNAPBACK}>[/url]</div>

I run 5W20 in mine and havnt had any problems yet. If your just rollin around in it as a daily driver and she's stock I'd stick with what mazda reccomends.[/b]

I owned an RX-8 before trading in for my Speed 6. I always used 5W-20 with great results. One time the dealer accidentally put 10W-30 in (because they don't read the owner's manual) and I could tell just by driving that something was wrong. The rotary winds up RPMs faster and therefore accelerates faster with the lighter weight 5W-20. Also, you probably already know this, but the rotary engine naturally consumes around 1 quart per 1000 miles so you need to add your own oil between your regularly scheduled oil changes.