fyrstormer

Hey, I said it was "my understanding", I didn't say it was God's honest truth.

Anyway, it does kinda make sense, because sulfur binds petroleum molecules together, especially the longer molecules, and dino oil invariably has some sulfur in it. Combining that sulfur with the extra-long ester chains found in the synthetic part of a synthetic-blend oil, and exposing it to large amounts of heat and very little oxygen (as would be the case in the exhaust cycle of a rotary engine) pretty closely mirrors the process used to make black tire rubber. That explanation also bears out the engine failures some people have had running cheap synthetic oils in their rotaries, as mentioned earlier in this thread.

invasion08

iTrader: (7)

If this was true then the same problems would happen in the piston engines as well. How can you prove that so called cheap synthetic oil caused engine failures?

fyrstormer

I don't know, ask the people who claim it happened to them. Engines are complex things and it's pretty unlikely that choice of oil alone is solely to blame for those failures, but that doesn't mean it has no effect at all, or else Mazda wouldn't waste time making recommendations in the first place.

You've been here a lot longer than I have, so I'll spare you the primer on the differences between rotaries and piston engines, but generally speaking piston engines that are in good working order DON'T burn oil, at least not in measurable quantities, and definitely not on purpose. Anyway, there are plenty of piston engines that get sludged up with the same crap I talked about above, such as the longitudinal 1.8t's used in B5 Passats and older Audi A4/S4s. Turbo engines are particularly vulnerable because the oil gets superheated inside the turbo's thrust bearings, moreso if the turbos are older non-water-jacketed types.

Soaring Eagle

Gosh - and Mazda got away with that? I have never seen in any owner's manual or warranty anything about a maximum speed to not exceed or the warrantly would be voided! Then they should either state that or put governors on the cars to prevent them from going over much lower speeds than most governors presently do. If it were me, I would have started a National campaign to boycott ALL Mazda products!

Wind Dance

iTrader: (7)

This is not true. Ask any 350Z or AP1 S2000 owners just for example.

lone_wolf025

As I recall most car manus say that up to a quart of oil burned out of like 3000 miles is considered "normal".

PaPaBear

I would not take a wheelbarrow to a Firestone dealer!

fyrstormer

"As a general rule..." means there may be exceptions but that the rule still holds true most of the time. Okay, so the only other production engine out there with a 9000rpm redline also burns oil; I can believe that. While we're listing exceptions, the LT1 Corvette engine also burns a quart of oil every 3000 miles, as does its close cousin used in small boats. However, in none of those cases is the oil burned on purpose like it is in rotaries; rather, it was too small of a problem in those cases for the engineers to waste time and money trying to solve.

Red_Fox

I switched to synthetic when i bought the car off the lot a year ago since then no problems and loving my 8

greg985

ur doomed....

sanyok

iTrader: (1)

^+1 part it out asap :P

on a serious note i'd have to agree just take it back and have them either print up a correct reciept or change it to conventional

REDRX3RX8

fyrstormer,

I gotta call BS on your tire rubber layer theory!

There is almost no sulfur in oil or you'd get too much sulfuric acid eating on bearing, etc.

All engines can carbon up, and I blame inferior gasoline as much or more than any oil burning on housing for lubrication. I mean the amount of sulfur the EPA has mandated to be scrubbed from natural gas, gasoline , and diesel the past 15 or 20 years is astronomical, so sulfur should be almost nonexistent.

IMO that the viscosity index improvers (STP) in dino oil to make 5w20 or 5w30 are way worse for making carbon on the apex seals than any of the new synthetic 0w20, 0w30, or 0w40 oils, but bargain gasoline definitely does not have good cleaning of any carbon that might get left in the chamber.

After Katrina, the EPA relaxed fuel quality standards to make our fuel shortage easier. I think some refiners are using that as excuse to keep cheating on gasoline additives. If you're worried about carbon in any engine you'd better be buying Top Tier gasoline (Chevron, Texaco, Shell, some others;look up Top Tier Gasolines).

We've all seen pics of rotary tear downs, and all I ever saw was clean, shiny housings; sometimes a little scoring. Sure carbon can build up in the apex seal and come off in small hard chunks to score the housing, but premixing with JASO FC or FD quality 2 cycle oil puts polybutenes in the gas making carbon that is softer and can be blown out easier.

Say my RX8 dies at 75,000 miles from apex carbon buildup. It'll use 5000 gallons of gasoline or less, but only meter about 10 gallons of oil to burn in chamber.

How can anyone claim its the oil without considering all that gasoline.

We've all had that nagging doubt after we've bought gasoline, and crossed our fingers until we could get the good stuff (TOP TIER) back in the tank.

humanwire

Sorry, didn't know anyone was still posting in this thread. The forums stopped notifying me!

Went back and had them change it back to standard, as well as put on the new tire. Chris, who is the service manager there, once had an RX8, and I figured he would know better than to do this without asking me. I actually felt more comfortable once I heard he was a former 8 owner, which is why I let Firestone change the oil in the first place. Even though he said he ran synthetic blend without any problems at all, it's still not what it says in my owner manual.

I was really excited to think I found a smaller, cheaper shop than the stealership, with someone I trusted my car with, but not so much any more.

Rioman

I took my RX8 to the dealership two weeks ago and they used synthetic blend for the oil change. So far everything seems okay. I would like to know other people's experiences with synthetic blend oils.

Jedi54

iTrader: (7)

synthetic is fine.
this engine will run on pretty much any oil you put in it so don't sweat it.
just pick a type of oil and stick with it.

40w8

RX8 or other rotary engines are easy to lube since they can't get to the high heat that German cars get or the water jackets seals will die.

You can use nearly anything, but I prefer Mobil 1 0w40, or Castrol, or Penz UP.

It's dirt cheap at Walmart, and very stout.

Some like the Shell T6 5w40 which is a higher additive cheaper oil for diesels.

Modern synthetics are best and no problem for any engine.

swoope

iTrader: (5)

seven year bump. thanks for searching!

beers

40w8

hey, you've been around long enough to know we'll take any oil fight, even if it's an old threadjack!