tazmaz

Can I mix Mobil 1 with the UK spec oil that they fit as standard?

Peggy

I don't think so man. Rotaries require totally different oils. I'm not too sure abou the consistency of these oils (whether their thicker or thinner) but I would not risk mixing it with a piston engine oil.

If you do, please let us know how it goes! ; b

FirstSpin

There was a poll about a week or two ago. Most guys are going dino (fossil-fuel-based hydrocarbon) all the way. That's what I intend to do until/unless someone can make a convincing argument to the contrary.....

Gord96BRG

Oh, really? And where do we buy this special rotary oil?

The funny thing is, my owners manual specifies that my RX-8 engine requires oil that meets API spec SL, viscosity 5W20. It makes no mention of synthetic being prohibited, and certainly makes no mention of special rotary oil.

This has been discussed extensively here - many people are unwilling to use synthetics because many Mazda dealers have been cautioning against it, due to leftover concerns from earlier generation rotaries. From a warranty standpoint, as long as the oil you use meets API SL, you're covered. From a technical standpoint, there is no basis so far to suggest that the use of synthetics will cause any problems, and there's always the proven advantages of synthetics.

For what it's worth, I'm using synthetic oil in my RX-8, and quite a few others are as well. It's generally not advised to mix oils of different brands just because of the differing additive packages, but as far as synthetic (Mobil 1) and the factory/dealer oil goes, synthetics and dino oils are chemically compatible and can be mixed with no problems.

(PS - for the record, there is no such thing as rotary oils or piston engine oils in general availability. There is one small vendor in US who claims to sell an oil that is optimised for rotaries, but that's just his sales pitch. There are oils optimized for diesel engines, but that's more for the different interaction with diesel fuel than gasoline fuel and higher combustion chamber pressures, along with their typical usage characteristics.)

Regards,
Gordon

tazmaz

Too late - just put in a pint of Mobil 1. I studied the manual and the specification of the Mobil 1 and it looks okay. I will check with my dealer tomorrow.

The Mobil 1 was left over from my Boxster - 4 years without having to take the top off the oil filler. I have had the RX (or rather my wife has) for 4 weeks and I have now put more oil in it than the Porsche had in 4 years (obviously excluding services).

The RX does compare very favourably with the Boxster - especially given in was 1/2 the price. Can't give the full verdict for 4 years!!

I will let you know if the rotor stops rotating . Look out for the headline "Mobil causes iMobility!"

Gord96BRG

The convincing arguments have already been made - you just need to search much further back than the poll!

MikeS

Mazda's website says that it does not recommend synthetic oils. However, it is a general recommendation and not specific to RX8. (I think I saw it in the "FAQ.") Of course, that is different than actually cautioning against synthetic. Inasmuch as the oil is actually burned in the rotary engine, I'm wondering what the combustion characteristics of synthetic is compared to regular oil? I'm staying away from synthetic.

(My Mini Cooper S requires synthetic, and I'm glad it does - I prefer synthetic. i wish Mazda would actually recommend its use.)

tazmaz

The bottle of oil that Mazda put in the boot (trunk) of the RX-8 when you buy it is actually synthetic. Their website clearly is at odds with their behaviour.

Odd

Baller

I use synthetic (Mobil 1) in my RX-8 and always will.
The new engine uses from one half to one eighth as much oil as the old version.
The 24 hours of Le Mans Mazda (4 rotar) used synthetic and won.
And yes Mobil 1 mixes just fine with dino.

Gord96BRG

But Mazda doesn't prohibit the use of synthetic oils, as they used to - that's a significant difference. Just as they don't recommend gasolines - you can use Shell, Exxon, etc., as long as it meets requirements. For engine oil, Mazda requires API SL, 5W20 - that's all. They don't require non-synthetic oil.

Regards,
Gordon

RX_999

I also use Mobil 1, Gordon is correct.
I have used Mobil 1 in all of my cars for 15 years.
Some thread also said Mazda did say Synthetic was just fine.

stickman

When I picked up my rx8 last week I was given a small supplemental booklet along with the owners manual. This booklet is produced by Mazda, not the dealer. It specifically says to NOT use synthethic oil in the rx8.

Baller

Can you scan and post this or give us the booklet number....my friend is a area Mazda rep. and has never heard about this booklet. Are you sure its not from the dealer?

stickman

Its called Mazda Driver's Guide, part number 9999-92-rx8d2-04.
It says to add only non-synthetic 5w-20 engine oil with sl or ilsc on the container.

Baller

Thank you stickman.
I e-mailed Mazda for a copy.

hotpot

You can find a scan of the page in the driver's guide regarding engine oil here. Scroll down to the bottom of the page.

https://www.rx8club.com/showthread.p...n&pagenumber=2

FirstSpin

While I'm planning to use dino; in all fairness, that document looks like a marketing brochure. Even though I'm in the chemical business and not automobiles; working in Technology and seeing some of the stuff our Marketing group spouts as fact, I would hesitate to take this as a technical fact. It could be the facts as some Marketing guy understood them at the time they designed the glossy. I'd venture to guess that a large percentage of these brochures aren't read by Engineering until long after they are released.

Obviously, I can't PROVE any of the above, but it's a possibility.....

Nubo

The debate is endless. What I'd love to see is a comparative teardown of 2 rotaries with similar mileage, 1 run on conventional oil and the other on synthetic. I'd then like to see visual evidence of whatever it is that synthetic supposedly leaves behind compared to conventional oil. All the arguments about synthetic burning/not burning will go on forever unless some real evidence is provided. So far the only thing approaching evidence imo are the reports of rotary users who've used synthetic for years without problems. I haven't read any that say "I used Mobil1 and it f***'ed up my engine", much less one of that kind that had any proof.

zerobanger

I always put Mobil 1 in my 3rd gen Rx-7. Mobile 1 is 100 times better for the turbo's since the heat transfer is much,much better with synthetic. Since the turbo's run cooler they last longer. Turbo's cost alot more than the engine does.

In my Rx-8 I use dyno juice.

Tirxer

how about castrol gtx?

bay

i have castrol gtx 5w-20 non synthetic (aka not the syntec subname)

Tirxer

so is it good?

Supraman

In Europe all we use is Synthetic.....that is what the dealer uses.

John Corbitt

I have used synthetics in all of my rotaries, including an ITS RX-7. I never have had an engine related problem. Two of my RX-7s had more than 170,000 miles on them when I sold them. One I Overhauled at 167,000 miles because I was doing a ground up restoration to it. The engine builder said after itwas pulled apart that it looked like new inside. The housings had slight heat checks in them. We replaced the housings and Apex seals just because the engine was apart. He said the berrings were just broken in and recommended I reuse them. After my breakin period on the 8, I will be switching to synthetic.

As for the burning issue, the synthetic does not burn completely like dino oil. That is no problem for the engine. It may, however shorten the life of the 80,000 mile waranteed Catylitic converter, hence the concern from Mazda.

Years ago Mazda Copm cars ran synthetic in their engines. They used two different types, one for the engine and another for the combustion chambers.

John

wquiles

I used Amsoil 100% synthetic in my '87 RX-7 from when I bought it used (about 24k miles) until I sold it with about 103K miles and the power/mileage did not changed while I had the car.

I use Modil 1 on my wife's 525i BMW and with about 107K miles, the engine still purs like a kitten.

My current E46 M3 can ONLY use synthetic oil due the strees/heat of making 333HP from just a 3.2L 6 cylinder.

I am a firm believer in using synthetic oils, and although I don't yet own an RX-8, if/when I get mine, I plan on using synthetic oils on it after the break-in period.