keynote22

^^^
mazdatrix used to have a piece in thier catalog about most synthetics not burning well. No one will dispute that mobile one is the ***** for piston motors...but as tom said..they dont burn oil as a matter of operation. Racing beat used to say that Amsoil was the only oil that would properly burn...course now they sell something else. Run the stuff for a few k and then pull a plug and see what it looks like.

TomsRX7

That's a good thought so maybe I'll try that. But don't you think looking at the spark plugs after a few K miles would be a hard way to tell? I think the problem would show itself till after a couple years and 30K miles, when the slow and gradual buildup is finally thick enough.

Also, keynote22, what you have you personally decided? What are you running? (since you are familiar with this issue)

-Tom

Joker

my totally biased and unscientific opinion--mobil 1 15w/50 is the sh*t

rotary-tt

I've been running Mobil 1 10w30 for 6 months. Seems to run smoother and the turbo spools faster. I'm making the switch to Royal Purple in a few weeks. It's about $5.25/quart after shipping directly from them on eBay: http://search.ebay.com/search/search...Sort&catref=C2

keynote22

I asked mobile one--who claimed thier oil will burn fine. Course what else would they say?

I talked to redline and amsoil who both sent me stacks of paperwork as proof about how clean thier oils burn and how well they hold up to breakdown. I also talked to racing beat who lead me to belive the following:

If I was going to use sythetic in my fd or 1st gen it would be amsoil. Good old castrol does the job just fine.

So for the price of a case of mobile 1 I have 2 cases of castrol and a mobile 1 filter. After all its the filter that takes out the stuff that damages the motor---the biggest mistake most people make is using a cheap *** filter with a paper element that breaks down after 3000 miles or doesn't filter enough crap out.

keynote22

regarding spark plugs: in the back of every haynes manual is a spark plug chart. I would suspect ash deposits----not that I think mobile one is a bad thing in a rotary motor.....I just think old school. If mobile 1 was going to do anything I think you would see it on the plugs fairly soon. If it wont burn, it wont burn.

RCCAZ 1

iTrader: (10)

Living here in the desert, summertime heat is a huge issue. If there truly is a 5 to 10F advantage in operating temps by switching to synthetic I'm even more interested. I've been running Castrol straight 30W but have been considering switching over to Royal Purple since it's readily available at any NAPA store. Are any of you who switched over to synthetic still using the Mazda OEM filter?

rpm_pwr

OEM filter / Mobil 1 here. No more puff of oil at startup and cooler temps have me very sold. I'm hooked.

-pete

TomsRX7

I'm not trying to change anyone's mind here, just want to give you some food for thought and play devil's advocate. I'm personally still on fence and haven't made the decision yet.

here's a quote from the Petit website http://www.pettitracing.com/sections/_faq.html#lessons:
.....some recommend synthetics, which can be run in rotaries, but may leave deposits as oil is routinely burned. For non-racing applications, stick to dino juice. I also use Pettit's Protek-R fuel lubricant, but some on the list have argued against it's claims... again, YMMV.

here's a quote from http://www.rx7-uk.co.uk/:
There are differing opinions on the pros and cons of using synthetic oils in a rotary. Synthetic oil is not officialy reccomended by Mazda, and has been blamed for o-ring seal shrinkage (causing oil seepage from between rotor housing and end-plates) and residue buildup on the rotors, causing carbon lock.......

The biggest threat to the rotary engine is probably carbon deposits within the combustion chambers. If the deposits build sufficiently that a sizeable chunk can come loose it can jam between rotor and housing, destroying the engine. The best way to prevent this is to regularly exersise the engine. Beware the cars advertised as 'never taken over 4000 rpm, never raced' etc. It really isn't good for them. Neither is pushing the engine too hard when it's cold. They warm up quickley though, and should then be allowed to rev freeley. The wankel engine is and always will be a racing engine.

And an other quote from http://www.marrsrx7.com/docs/Oil%20f...%20Engines.pdf:
The Oil Metering Pump injects a deliberate amount of oil into the your carburetor for the engine to burn. The nature of non-synthetic oils is that they leave a slippery residue even after a combustion process. This residue
is what hangs around inside your engine to keep the apex seals "WET". Synthetic oils burn too clean to lubricate the compression seals in a rotary. Once it ignites, it's gone. It is known that Zero Weight Mobil 1 will give your Spec 7 more HP especially on the top end but do you want to sacrifice engine durability? So many decisions to make.

juliof

I run a mixture of 2 quarts mobile1 15-50 and 2 quarts castrol 20-50 gtx and I replace it every 4 months no matter how many miles.This makes better sense too me than going full synthetic and replacing every 3K that gets very expensive.Plus 13BREW #1 failer are caused by weak o-rings not wear and tear , I would rather spend the extra $$$ on upgraded cooling system.

mecman

iTrader: (11)

I switched to Mobil 1 after reading all the pros and cons. I immediately notices an easier start, smoother idle and faster spool up on the turbos. I think the new synthetics acutally burn cleaner than dino. My motor has 56K orgininal miles with reliability mods and runs great.

SleepR1

Mobil 1 15W50 leaves a very fine film of oil after it's done running through the funnel after pouring. If that fine film of oil sticks to the funnel, the same film stays on the motor parts after shutting her down. Thus when you go to start her up the next time, the fine oil layer protects the motor during the start up process until the oil can start running through the motor again. This is yet another advantage of full syth over mineral

rotorbrain

put some conventional oil in your fingers and rub them together. now put some synthetic oil on a CLEAN set of fingers and rub them. i noticed a little bit of a difference. the conventional seemed to allow me to "pierce the bead" between my fingers. i was literally rubbing skin on skin. my fingers were sticking together. the synthetic oil (has smaller molecules); however, was slippery the whole time. the synthetic oil has the ability to work itself into the small cracks in the surface of the metal. it "fills up" the cracks. that is part of the added protection.

paul

allenbillings

You young guys crack me up! Marvel Mystery Oil has been around since the '20s. It was originally recommended for use as an upper cylinder lubricant that was to be mixed with the gas in the gas tank. It also does a fine job lubricating air tools, especially if you use a line oiler after your compressor. (I have a 1/2" Ingersol-Rand impact gun that I bought in 1973 and it has never had anything done to it to this day!!)
Mobil 1 is soooo slick that when I put it in my new Chevy 454, after it first came out, I was using 3 quarts of oil every 300 miles! I found out that I needed to break in the engine on dino juice BEFORE using Mobil 1 because it was too slick to let the rings seat properly. I ran Valvoline 10-40 for 5,000 miles and then switched back to Mobil 1 5-30 with great success. I like the stuff, but I don't like the idea of putting it in a rotary that still has a working oil injection system. I'd use the Mobil 1 in the crankcase and the MMO as a premix. That way you get the best of both worlds.

By the way.......No disrespect intended when I called you "Young Guys". I used to get the same thing before I became the "Old Guy".

Rsex7

I used Mobil 1 on my first motor which only had about 34,000 miles on it when it blew. My mechanic said not to use synthetic oil on rotary engines because the film of the oil is too thin, and rotaries need thicker film to burn, so I learned my lesson and using Castrol 20/50, and almost 100,000 later car has been running great.

Kento

No offense, but your mechanic doesn't know what he's talking about. "The oil film is too thin?" On what? Modern synthetic oils' viscosity or its film properties have little to do with its ability to protect and lubricate; the additive package mostly deals with that. "Thicker oil to burn?" Neither has anything to do with the other; this statement doesn't make sense.

Your previous motor probably had other issues that contributed to its demise at 34K.

mecman

iTrader: (11)

I switched last year and love it! The car runs smoother and revs faster. Temperarture is definitely lower.

All the latest info seems to indicate that the initial findings from Mazda no longer apply. I think the technology has improved and the issues in the past don't matter anymore.

allenbillings

I'm wondering if you guys that are running Mobil 1 are still using the OMP. I can see where the thinner viscosity of Mobil 1 might result in lower compression since it DOES actually leave a thinner protective film on the engine parts.
A thicker viscosity oil might help seal the chambers and result in better compression, especially during initial startups after sitting for a while.
We use Valvoline pure synthetic in our other cars (Supra Turbo, Chevy Pickup) and are quite happy with it, but I still don't like the idea of using a crankcase synthetic with the OMP. I have been using the adapter kit and 2-stroke synthetic in the RX7. That way the wife doesn't have to worry about premix at the pump and we aren't running crankcase oil with additives through the combustion chambers. This is a '91 NA with 94K on it and it still runs just fine.
Your thoughts on the matter would be appreciated even if they are not flattering.

Kento

The oil doesn't seal the rotor/combustion chamber, the apex seal does. The belief that thicker viscosity oil will result in higher compression is a myth. Also, the belief that a thicker viscosity will automatically result in a "thicker film" that offers better protection of internal engine parts is a myth as well.

While using dino oil won't result in your rotary seizing or blowing up, you should get to know the term "volatility". This is an oil's ability to resist degradation of the base oil and loss of additives due to high temps (which rotaries obviously have an abundance of) over time. The vast majority of synthetics easily outperform dino oils in this area by a wide margin.

You also mention becoming hesitant at "running crankcase oil additives through the combustion chambers." You should know that dino oils often need MORE additives than comparable synthetics to meet the latest API standards. This is because their base product upon which the oil is formulated already performs better, so they don't need large quantities of additives like polymers and friction modifiers.

tmiked

1) Synthetics, e.g. Mobil 1 , do NOT 'leave a thinner film'
The thickness on the film just depends on what weight of oil you are running. Specifically the 'W' number at room temperatures. The synthetics do adhere to metal better than conventional oils so the film will last longer. That’s why synthetics are touted as reducing wear. Virtually all wear occurs at startup and with a synthetic you will have a better protective film on the bearings at startup.

2) Mazda use to not recommends synthetics because they did not burn as easily as conventional oil and left a residue. As there are now plenty of synthetic two-stroke oils around some companies have clearly solved that problem.

3) From the information on the Mobil 1 web site, it appears they feel confident they have solved the problem too.

4) My BMW with an engine that cost over $12,000 to replace recommends 15,000 miles between oil changes. I am comfortable driving my RX-7 at least 5K between changes unless I am making a lot of short trips, which will dilute the oil. For very low use cars, I would say change the oil at least every six months.

5) All these post about 'My car runs much better with 'so-and-so' oil' are total BS. Within reason, oil has no affect on the performance of your car, but maximal affect on the longevity. 'Placebo effect'

SilverRX7

Do you have any data showing that it doesnt affect the driveability of the engine? I too have noticed a lower idle speed and smoother startup/idle.... so have alot of other people... thats alot of placebo's...

BenzaLee

I used mobile one until I blew my engine. I think it was alright but when I switched to it I couldnt really tell any difference because it was using royal purple before from the previous owner. But any way when I picked my car up from Rotary Performance they told me to stick with castrol 20w 50. They said they had had mixed results with mobile one and royal purple So I dont know weather to switch back or not The one thing I have noticed is that it seems to run a little warmer. But they also changed the thermostat during the rebuild so who knows. Anyone use redline?

Rx-7$4$me

WHAT TOD DOO OOOO OOO ... this on-going debate is making ME GO CRAZYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

DRAG0NEER

what's wrong with using castrol???

Howard Coleman

iTrader: (6)

an interesting thread... i am delighted to see how many people are pleased with Mobil 1. i bought Roger Mandeville's IMSA winning RX3 in 82/3 and he and i converted it to SCCA GT3 specs. i raced it for 6 seasons during which i placed 2nd once, third twice and 4th twice at the Runoffs at Road Atlanta... (that was the real Road Atlanta before they put the girlie-man chicane in at the end of the long back straight.) competition in gt3 back then was fierce with much deeper fields than today. Roger's motors ran between 5500 and 8500. if you run up front your foot is either on the floorboards on the accelerator or the brake for 35 minutes.. in 86 i switched to Daryl Drummond for my motors. Daryl's motors ran from 7000 t0 10,000 rpm for 35 minutes. all 6 seasons i ran Mobil one. not only in my engine, but gearbox, rear end and wheel bearings... FYI, the F-15 uses Mobil One in it's front wheel bearing. zero to 180 mph instantaneously... i had one motor failure (apex seal). i was gridded 4th going into the last qualifying session at the Runoffs and decided to bump the rear gear ratio a tooth (quick change rear end). that would mean i would be turning 10,300 at the end of a mile long straight. Daryl said the chances of it holding together at 10,300 in top gear were 50/50. on the second lap i popped a seal at 10,300. with mobil one i ran over 72 national races, 6 Runoffs and lost one motor. no transmissions. no rearends. no wheel bearings. it is the cheapest thing you can do for your car. i recommend for ultimate performance you ditch your external oil pump and use premix in your tank. i suggest any good quality 4 cycle oil... no synthetic in the chambers. don't forget mobil one lube in your trans and rearend.
howard coleman