Texas Heat? 10w40?
 

Turns out engine is just fine in my RX8,
So i am going to change oil next week.

Should i use 10w40?

my 17500rpm 600cc engine takes 10w40...

And your point is...?

0w10 all the way !



seriously, SEARCH

There is a lot of info in this forum regarding oil, read up and see what you think. You might consider going with the RX8 owner's manual recommendation of 5W20 until warranty on engine has expired. I think the rest of the world recommendation is 5W30 so that might be OK. Many favor a heaver oil like 0W40 synthetic or even 20W50 dino. Whatever you decide check the level often and change the oil often.

i run 10W40 in the summer and 10W30 when it gets colder. 38K miles and no issues. not that its completely relevant, but the first and second generation RX-7 uses 20W50 in the summer and 10W40 in the winter months.

It should be just fine. Just make sure you check it every gas fill-up and top it off when needed.

My opinion is that you could go to your auto parts store, put on a blindfold, and grab a random case of engine oil. It really doesn't much matter.

The important things are checking it often, and changing it (and the filter) on schedule.

0w40 is about the same thickness as 10w30 at 20-30-deg f, and 40 weight in the summer, thus no going back and forth.

There is a chart from the Australian RX-8 owner's manual that ASH8 first posted here, and which has been reposted several times. It shows recommended oil weights for various temperatures. For weather like you usually have in Texas this time of year (lows above freezing, highs not tropical) Wingznut's answer is correct.

Try searching for that chart. I've lost track of which threads it appeared in. One of the oil threads, but that doesn't narrow it down.

Ken

I wouldn't recommend anyone following this procedure.

I recommend a 10w40 or 20w50 on all my rebuilds due to the wear on the main bearings I have seen w/ a 5w20 Mazda recommendation and my past experiences w/ these motors.