Gomez was kind enough to post this picture of the "Recommended Oil" page in his Australian owner's manual:


(From Gomez's post in the "Issues & Problems > RX8 Engine Replacement - BAD NEWS" thread)

I compared Gomez's page to ours here in the US. (My digital camera won't do the page justice -- perhaps someone with a 2005 model and a scanner could capture pages 8-12 and 8-13 in the owner's manual for us.)

While Gomez's page shows numerous grades of oil for various temperature ranges, my page shows just one: 5W20. This is true in the "US & Canada" section and the "Except US & Canada" section.

Contradiction? You bet! Is anyone curious why that is?

Well, I may have found the answer. This letter to vehicle manufacturers from our (in)famous Environmental Protection Agency dated 7/31/2001 explains how the manufacturer must "promote" the use of whatever oil was in the pre-production test vehicles. Manufacturers must provide(Note that it does not say they can specify the use of a higher viscosity in extremely high ambient temperatures. )

They also must clearly indicateThere are many other legal requirements spelled out in the letter, but I think those two are the most relevant to discussions here.

I'm not an alarmist, so I'm not going to "convict" the EPA or Mazda for anything at this point. However, I do think it makes an interesting case that can be discussed here. Given that our USA manual is obviously influenced by the EPA, What grade of engine oil is best for our engines? I realize this is almost a religious debate, and I'm not trying to open another "synthetic/non-synthetic" can of worms again... But when it comes to protecting my vehicular investment, the last person I'm going to ask for advice on this is some bureaucrat in Ann Arbor!

 

I've used 5w30 ever since the dealer put in in on my second oil change. 4 port engine with 44100 miles and still purrs like new. The car's lived its entire life in the South's high temps and humidity.

 

....the EPA mandated the 5W20 spec, HOWEVER, a good, name-brand GF3 5W20 has been shown to be an excellent oil.

Wear analysis, thickening over time, sludge formation, remaining life (TBN) and actual results have shown that these oils are a step-change above the old 10W30 stuff.

The results probably reflect the difficulty of formulating an oil of this quality without resorting to synthetic ingredients. It is really difficult to get 'good-old-dinosaur-juice' to meet the GF3 requirements. Most brands are semi-synths, and the prices reflect that.

S

 

GF-3 is SO 2004, try the new SM/GF-4 oils for a change

 

Give us brand names....

 

Awesome -- Thanks, abbid.

Now if someone could do the same for the 2005 manual, that would be "awesome squared."

 

Really it mostly depends on your location and weather, and if U want to use a lower weight. 5W20 will only be good in that 5-20 temp and not good if u go over or under these temp changes by much. that way during the winter u can change the oil to a diff weight and during the hot summer u can change to another weight.

 

I did my first oil change at 1000 miles with Quaker's Advance Q 5w20, Full Syth oil

the car actually performs *I think* better than original.

Im going to change my oil again soon, at maybe around 2500 Miles, since Im waiting for new K&N oil filter to come in. (probably by thursday)

Why Full Syth ? I mean since the manual did NOT say you should not use Synth Oil. remember all these oil companies completing with each other day after day, forcing them to make better products.

Im going to run Pure Full-Synth oil, and see how long till my engine dies , I dont drive much since I live in NYC, but I already have hmm 2100 miles in just a little more than a month.

 

What is up with the apparent temperature discrepancy with the 5W-20 between the 2 manuals? In the Australian manual it doesn't appear to go up to 120 F while in the American version it does.

 

I hadn't noticed that, Vizacar -- great observation!

 

Current tech 5w-20 oils are far superior to older 30 and 40 wts.

These same type of conversations started when the 30 wt oils hit the market.

"OMFG your engine will be destroyed!!!" 5w-30 is WAY too thin! WTF U STUPID!!!! ITS EPA!!!

I'm sure the same thing will happen in a few more years when everything drops to 10wt, and finally 5wt oils.

Technology isn't static, it improves over time. Change is good not bad .

Research is your friend!

http://www.bobistheoilguy.com

Quick example...redline 5w-20 has a higher HTHS # then Mobil1 10w-30.

 

Here are the pages from my 2005 (CDN) manual

2005 PDF

 

So if 20-weight oil is rated for up to 100 degrees, what happens to the oil when it's 120 in Vegas or elsewhere?

 

My manual matches the Canadian one. It goes to exactly 120 F.
Gomez, does it go to 110 in the Australian manual? The picture above is kind of skewed but doesn't look like it goes to 120F.

What is the actual 5W-20 specs?

Could they have made it look like it goes to 120F, in the NA manuals, because of the EPA requirements, not taking into consideration the extreme S & SW temperatures, especially with the record heat waves this year?

 

I have been using Motorcraft 5W-20. It is a very good semi-synthetic made by Conoco. There have been many good reports on this oil at the BITOG forum. This is the used oil analysis for my RX8:
http://theoildrop.server101.com/cgi/...c;f=3;t=002559

The new 5W-20's have a very robust additive pack, and are all severly hydro-cracked at a minimum. They have a good track record in Mazda, Honda, and Ford products that recomment this weight of oil.

 

In my manual 5W-20 goes to 115F, actually....

 

Mine too. Many thanks to Flop for taking the time to scan those pages for us.
That's the same question I had in my head but was a bit hesitant to post!

Unless there's a valid reason to assume that the same oil would perform differently at the same temperature in different parts of the world, then I think Mazda has some explaining to do. If the EPA made them do it, then they would need to say that in no uncertain terms.

 

Castrol GTX 5w-20 (look for the new SM/GF-4 rating on the bottle!!)
Motorcraft 5w-20 (ditto on the SM/GF-4 label)

2 not too pricy, but well performing oils for your 8 :D

 

the mandate from the epa is that the company must recommend the oil it uses in MPG and emissions testing. most companies are switching to 5w20s because they have found they get better mpg ratings with them. that helps them stay within the CAFE standards.

this has all been said here before by me and others

 

Okay then, lets say you are right (and trust me, I believe that the 5w20 thing is for fuel economy)...

What is a good 'high tech' oil for our Rotaries that we can get stateside that is a pure mineral based oil in the RIGHT weight (5w30 I assume is the best one for most of North America). We were at 95°F today and I'm up in Ottawa, Ontario

Can I just switch over to the Castrol GTX 5w30 from the 5w20 and expect a little less fuel economy and longer engine life in this heat? It sort of sounds like it from all the posts I have been reading (all over the net, not just here)...

 

the oil viscosity will only affect cold starts, once the car is warmed up the oil temps will be higher than 180 F and sometimes go as high as 230 F or more if you race it...

 

i'm sticking with 5w-20 in the foreseeable future, as I have yet to see any major oil breakdowns due to excessive heat in the past 2 oil analysis that I have done on my 8. Both times the results came back well within acceptable range, no problematic oil breakdown at all :-)

 

doing a UOA on your oil is probably one of the best diagnostic test you can do to check the health of your renesis motor, it's like doing a blood test, you find out quite a bit about what's going on inside the engine, without actually having to open it up :p

 

OK, I just posted in the engine thread because I am convinced - all evidence says so - that the oil grade recommended by Mazda in US is wrong for LV temperatures. Even the plot in the Australian manual is misleading - when did a W20 oil go to the same high temp with a W30 oil?!? Look at all the other grades in that plot; they all line-up. Lower limit comes from the 5, 10 or 15 number before W. Upper temp limit is the same for all W20 and smaller than for all W30 or W40. So the arrow on which both 5W20 and 5W30 stay is wrong. Your 5W20 does NOT go beyond 100F - see the 20W20 grade. The 110F limit is ONLY for 5W30. They do start at the same temp, but that is useless during summer month.

Regardless of brand or source (dino, synth), an W20 oil will never ever be as viscous as a W30. That is for the fresh oil, true. From there, some break down more than others. An old W30 formulation (say, SJ) will be probable breaking down at 5000 miles to match a great W20 modern one (say, SM). But up to that point, it will still protect your engine more. As I said, the 5 or 10 or 15 in front of the W are useless for summer - those are to protect your engine during starts in really cold temperatures. So yes, do use different oils winter vs summer - this way you save money and have better protection in summer.

OK, since people like Castrol GTX, use 5W20 in winter (3 month in most of Northern NA - where you get snow) and 10W30 in the rest of the year (or 10W40 if you track your car). Change it 4-5000 miles, depending on how hard you drive. Or, if no snow ever messes with your driving experience, use 5W30 year round (unless you track the car - see above)

And if you change your oil at 3000 miles, it will not make a difference if you use a 5W30 modern dino (API SM) or full synth. It might make a difference more, depending on the brand, if you change at 5000 miles. Both API SM Castrol and Motorcraft API SL in 5W20 are good stuff (but not for above 100F constant temps for weeks - then you see the car break down if you are missing one oil cooler - like the AT does, or if you drive too hard. If you don't drive hard enough, the same AT will carbon'lock. Talking about a picky car - AT takes on any competition hands down, as it needs the right oil for the temperatures outside, and be driven hard enough but not too hard....

So much for rocket science....

PS yes, I have an AT an I love it - keeps me always on the edge - cannot ever neglect it, it's so demanding :o)))))))))))))))))))) And I use Castrol "new dino API SL" 5W20 because we are 99% of the time bellow 100F (outside temps) in NJ

 

can't stress enough: UOA will give you FACTUAL data to determine if your oil is doing what it's suppose to do, not all these educated hypothesis :o