CVale127

iTrader: (17)

Hey guys, my rx-8 has been running on Castrol Syntec 5W-30 for the past 4000 miles. I had previously changed the oil with regular 5W-20 oil before going the synthetic route. I also chose 5W-30 because I've read online that everywhere else in the world besides the U.S., 5W-30 is recommended for the rx-8 and is better than 5W-20 for this car.

I must say that I have noticed my gas mileage decrease ever since I changed the oil, and im pretty sure its because i put in 5W-30 ? before i was getting 19-20 mpg and now I have been getting 16-20 mpg with mixed driving. I'm gonna do another oil change next week and I'm trying to decide wheter to put in Royal Purple 5W-20 in the car to raise my mpg's, or Royal Purple 5W-30 ?

My theory is that 5W-30 is recommended around the world mainly because of the performance during warm conditions (better heat protection for the engine than 5W-20) both should work the same in cold weather because they are both 5W oils....but since synthetic naturally is way better than mineral oil as far as cold and hot climate perfomance goes...I'm thinking the use of 5W-20 synthetic oil should be just as good if not better than using a 5W-30 mineral oil + id be getting better gas mileage....So once again the question is: Royal Purple 5W-20 or 5W-30?

What do you guys think ? Id appreciate all the advice. Thanks!!

laythor

i think you should read the 100 threads and 30,000 posts about which oil is best.



i'll save you the trouble, there isn't one best oil.

REDRX3RX8

0w40 or 5w40

05rx8mazda

iTrader: (4)

^^^^ also premix some 2 cycl tcw-3 oil in your gas tank.

Albmw

there must be a -40 somewhere at least! 20 and even 30's are way too thin when things get hot! The 0w, 5w or even 10w depends on where you are when it gets cold! I always use a 10w-40 now, and it's just fine.... don't really care about the mileage, prefer to save the engine!

Flashwing

Considering the operational temperature of your motor does not change more than 5 or 10 degrees between winter and summer you can use the same oil year round.

The notion of using a summer and winter oil is a myth and a waste of money. Pick an oil that works well for you in the winter and use it all year round.

nycgps

iTrader: (1)

oh another oil thread

*popcorn*

IBTL !

CVale127

iTrader: (17)

1. I don't live in an area where it gets EXTREMELY HOT like arizona or califonia lol.

2. Quality Synthetic oils (and synthetic in general) don't thin out during high heat as easy as mineral oils do.

nycgps

iTrader: (1)

You forgot about film strength.

You dont need extremely hot places like AZ or CA or Africa to use heavier oil.

People who said these are usually the people that never have Oil temp gauges installed on their 8.

When you do, you will know what kind of oil temp you're seeing, even when its 20f degrees out.

CVale127

iTrader: (17)

Well Royal Purple states that their oils have a high film strength as seen here http://royalpurple.com/rp-performanc...html........so I guess they would deff be a good choice. What kind of oil do you use on your 8 ?

nycgps

iTrader: (1)

I use Peanut oil.

Taste good !






well, I use 20w50, and ppl hate me for that

laythor

OMG

stop making threads about OIL!!!!

there are dozen and dozens of threads that have said exactly what everyone has posted here. L2READ...


even my rant here has been done dozens of times by dozens of people.

CVale127

iTrader: (17)

Sorry dude....but there hasn't been an oil thread asking my EXACT question.

nycgps

iTrader: (1)

actually ... there were TONS of the thread with the EXACT stuff that u just asked for ...

Flashwing

There is an overwhelming wealth of information regarding viscosity and it's relation to engine performance as well as protection. I know because I've greatly contributed to that discussion.

There are various oil threads which are easy to spot because they have about 50+ pages of posts.

luv4eternity

cant tell u ...im still trying different oil change every change ...just to get a feel which is better....but i keep 5w20 on any oil i get ...

swoope

iTrader: (5)

have run lots of stuff. from rp 5w 30 to rotella 15 w 40. what changes gas mileage is city driving.. and traffic.

beers

dezodwest

RP oil is horrible. It breaks down faster than anything I've ever used, and refuse to put it in my Mazda.

swoope

iTrader: (5)

funny,

i ran it for 55k miles, no issues.. you have any other data on that? what weight?

beers

ArXate

Would you rather use dino or synthetic peanut oil? This question might help CVale and I KNOW it has never been asked before.

BTW, you prefer Olga Kurylenko or Megan Fox?

Huey52

iTrader: (2)

5W-30 year round in relatively cooler New England for me.

CVale127

iTrader: (17)

Jesusss....thats some thick oil LoL. U ever have any issues with 20W while starting the car up in the winter ?

SayNoToPistons

iTrader: (8)

I also use 20w50 for summer. 10w30 for winter.

ArXate

This is a very unique thread. I like it. Maybe make it a sticky?

nycgps

iTrader: (1)

true ...

Hmm, I dunno, I never had a Synthetic peanut oil before. where did ya get them?

I only had some all natural ones that was made from REAL peanut.

when I turn my engine on OMG it smells great !

I prefer Megan Fox, Just don't look at her finger and it will be fine.

no.

ppl using it for years so I dont see why not.

I left a bottle of 20w50 outside for a day on 20 degrees weather, it thicken up a bit, but nothing really as scary as people thought it would be. of course oil degrades over time, but Synthetic based would be ok for at least 5 K miles.