jmclark

So I bought my 04 RX8 6spd about a year and a half ago. I bought the powertrain warranty just in case and it just paid off hardcore. I bought the car at 65k mi, started having the dreaded cold start problem about 72k mi and got the engine replaced under warranty at 82k mi. After the replacent my trusted mechanic told me that the car already had a remanufactured engine in it which tells me a lot about the previous owner. Anyhow the car runs great now.


I've read the RX8Club.com forums for a while and learned quite a bit from you guys. I just signed up because I've never needed to ask a question after searching and reading the threads. I've read every oil debate forum until I couldn't stand it or wasn't learning anything anymore. I DO NOT want to start an oil debate thread! I have a fairly specific question.


I live in the Oklahoma City metro area. We have average winter lows of 28F and a record low of -11F. We have average summer highs of 94F and record highs of 113F. It also gets very humid in the summer months and we can have some pretty good wind chill factors in the winter. My car is a daily driver. It has to get me to work every day. I probably do about 2/3 highway driving 1/3 city streets. I've read us much as I can understand about oil viscosities. I plan on using synthetic oil, considering Royal Purple. I plan to "migrate" oil viscosities from winter to summer since we have such extremes. I've read that a good portion of engine wear happens while starting the engine and a lower viscosity(xxW for cold oil) is better in cold weather so I should probably be using a 5W in the winter. I care more about engine life than performance and would sacrifice a little mpg for engine life.
What weights would you use for each season?


I'm thinking 5W-20 or 5W30 are best for winter and have no idea what might be good for summer. If I'm changing my oil every 3 months I can use a different weight each season? Fall and Spring are generally fairly mild temperatures so I could pick a happy median.


Any additional general maintenance suggestions are greatly appreciated.

Thanks Guys!

ken-x8

Since you've read all the oil threads, you've come across the oil chart from the Australian owner's manual. That gives specific answers. In a temperate climate almost anything would work. But you've got some extremes.

You can use different weights by season. IMHO you're in the right ballpark for winter. A 0w something would be better when it's sub-zero. For those summer temps, step up the high end - 10w40 or similar. As long as you're using multi-grade, you don't have to fret about the summer or winter weights being wrong for the moderate spring/fall transitions.

Don't use Royal Purple.

Ken

jmclark

I saw a lot of references to the chart but never did actually see it. And I've been reading on my phone. Just found it in a google image search though. Funny how different it is than the US chart.

Thanks!

ken-x8

The US chart is based on the mantra to use thin "energy saving" oil to boost corporate average fuel economy. That helps gas mileage by such a small amount it's amazing they bother.

There's also a version of the shop manual that lists all of the oil weights in that chart (maybe mover), but doesn't say anything about what tempearture range for each. So this site isn't the only place with no definitive answers.

Ken

RIWWP

iTrader: (2)

Cold start problem? That would be a coolant collecting in the engine overnight from a coolant seal failure from overheating it. The "dreaded" starting problem around here is more accurately the hot start problem, which is compression loss. Not sure if that was a typo or not.



No, actually, that doesn't tell you anything about the prior owner. The 2004s didn't have enough oil injected on the original flash, and many failed really early due to no fault of the original owner. Some may have also been replaced due to other factors like ignition failure that was misdiagnosed or fuel pump failure that took out the engine with it.


Keep in mind that when the engine is up to temp, it doesn't matter what the ambient conditions are at, a 20 weight oil is still a 20 weight, a 30 weight is still a 30 weight.

Also, keep in mind that the thinner the oil cold oil weight is, the better the starting protection will be, even in summer.

Consider a 0w30 or a 0w40, since it will be the thinnest in winter and summer on a cold start, and offer enough bearing protection once up to temperature.

Sato Tatsuya

Hi RIWWP!

So I just purchased a 2004 RX-8 yesterday (YAH! ), and been wondering about this too! I know that people recommend 5W20 for the engine because it is recommended. I live in Ontario, Canada, so it does get pretty cold here as well, especially this winter season. In any case, it makes logical sense for me to switch to 0W20 or 0W30 all year-round, but should I? Will it damage the engine? I don't want to run into any problems with the engine.

Please share with me some of your wisdom!!

- Christopher

RIWWP

iTrader: (2)

You can run just about any oil you want without causing damage to the engine. Fresh oil is far more important than the oil weight, since oil loses viscosity over time.

Sato Tatsuya

Thank you RIWWP! I have been searching around for discussions/threads on oil viscosity and which oil is better for the RENESIS. Can you provide me the link to a couple of the threads? I was unable to find any threads through the forum search engine. It is pretty broad, even when I go to advance search to try and narrow it down.

RIWWP

iTrader: (2)

https://www.rx8club.com/new-member-f...thread-248952/

Sato Tatsuya

Thank you RIWWP! Sorry to have made you find the link for me! Thank you very much!

jmclark

hanks for the answers guys! Considering. Mobile 1 synthetic 0w40 as it's the only 0w >20 oil available at my local auto parts stores.

I do have another hopefully simple question though. I've got about 400 miles on the new motor now. We had a nice stretch of sunny skies and warm weather for about half a week then a relatively cold weekend. I hadn't driven the 8 all weekend and Monday morning when I headed out to work the battery was dead. I got a jump and made the ~20 mi highway drive to work. It started, with some hesitation, when I got off 8hrs later. I put another ~20 mi on it with about 3 clean starts. Went ahead and had the battery tested at O'rielley and it had low cranking amps, ~350. Got a new battery under warranty. When I installed it it started very rough, felt like it was going to die a few times before it came to a smooth idle, it did this for about 3 consecutive starts. O'rielley tested everything again. Everything looked good as far as the alternator and battery goes but the test showed ~8.4v while cranking. The guy said that it was most likely my starter, which makes sense to me.

After another 20 mi or so and about 3 more at atempted starts I'm not noticing any trouble starting the car as I did when I first installed the battery. I can see how my starter would be shot after starting my old low compression motor for a while.

So I'm considering buying a new starter and possibly doing the BHR ignition upgrade after. My trusty mechanic put new spark plugs in with the engine. So I thought if the starter is dying and I'm gonna replace it I might as well make sure my ignition system is in as tip top shape as my new motor.

I know the O'rielley guy isn't a rotary expert but his advice seemed sound, and the ignition system isn't really different from a piston engine. Just want to make sure I'm on the right track here.

jmclark

I was previously referring to the hot start problem. Started "okay" when cold, wouldn't start at all when warm at the end of it's life.

rotarywanker

M1 0w40 is very good. Members here have sent used samples for lab tests and gotten great results. I use it in my RX-8. Another good option is Rotella T6 (5w-40), and it's pretty easy to find cheap. Either would be great for you year round.

Just for the record, there is quite a lot of misinformation on this board with respect to oil 'thickness'. 0w40 will never be too thin for you - summer or winter. With modern multisynth oils, 'thickness' is not defined as it used to be and is very misunderstood. For instance, M1 0w40 will be thicker than a 5w30 at any realistic operating temperature. It just happens to do very well at low temperatures. Too much to write, see below for more info on this:

Why would M1 5w30 be thinner than 0w-40? | Passenger Car Motor Oil (PCMO) - Gasoline Cars/Pickups/Vans/SUVs | Bob Is The Oil Guy
Viscosity Charts - Bob is the Oil Guy

RotoryVirgin

I will live by this man's example
245k on royal purple 5w20/15w40

https://www.rx8club.com/showthread.p...536&styleid=21