Rotarykid7

i was talking with my dad last night about using synthetic. he's an old school muscle car guy and said that he was always told that if you've been using regular oil that you shouldn't switch to synthetic because it can find leaks that were sealed before. but a guy i work with told me that he was always told that once you switch to synthetic that you need to stick with synthetic for the same reason my dad said. anyone have any experience with this? i know that you need to use premium synthetics I've just never seen anything about if its safe to switch over?
-Komisor

therotaryrocket

first of all it supposedly doesn't burn well so isn't suggested by mazda for use in rotary engines. now some synthetic facts, they can be mixed with conventional motor oils, you can switch back and forth. I got these facts at work advance auto parts. it does sometimes cause leaks, but is much better protection, i guess you can try it, if it doesn't work than switch back but i don't know if the leaks would remain.

Icemark

That is an old wives tale, back from the days of the original synthetics

Tell your dad he needs to get into the 90's.

Icemark

an even worse old wives tales... time to get into the 80's

KatakanaKarl

If you disable your OMP, plug your oil injector holes and premix, you can run sythetic without any worries, since none is getting injected into the chamber.

Before you switch you would have to drain your oil cooler (preferably flush it) to get any remaining dino oil out, I've heard the cooler holds about a quart.

This is what I'm planning on doing next oil change.

Icemark

No [insert drug use slang here] allowed on the forum.

Each and every synthectic made burns at or below 500F (considerably lower than the internal combustion temp of a rotary engine).

Each and every synthetic made is compatible with conventional oils, so there is no need to drain the oil cooler

KatakanaKarl

Huh? Did I say something wrong?

Icemark

Each and every synthectic made burns at or below 500F (considerably lower than the internal combustion temp of a rotary engine).

Each and every synthetic made is compatible with conventional oils, so there is no need to drain the oil cooler.

This thread will be closed very very fast if there is even one more crack head post about a synthetic not working in a rotary engine, or that the synthetics are not compatible or require minor engine work such as killing the MOP system.

KatakanaKarl

Oh, I didn't know that. I had read somewhere on this forum that one needed to drain the cooler when switching to sythetic.

Thank you for clearing this up for me. It eliminated one step from my project.

Icemark

and see you helped perpetuate that lame *** myth by your first post in this thread...

Back in '86 Redline and Amsoil proved that good quality synthetics were safe to use in rotary engines, with fully functioning stock MOP systems.

Please read the FAQ for FC sticky thread before posting

Evil Aviator

That is a problem with using HD oil in an engine that used regular oil for a long time, regardless of whether the HD oil is mineral or synthetic based. Just stay away from the HD oils if you think this will be a problem.

I don't recommend using synthetic oil in the engine except for competitive racing events. It simply isn't worth the money on a street car when you consider the short oil change interval and average burn-off rate of a rotary engine. However, synthetic transmission oil, differential oil, and bearing grease last 30,000 to 60,000 miles, making them a better buy.

Icemark

I agree completely, but for the overly rich, who have money to burn, good quality synthetics are fine.

Mason Rx7

My first Rx-7 was owned by my uncle who ran it with Mobil 1 since the day he bought it back in '87. When I picked it up it had 94k on it and ran great. He parked it during the winter and kept it as a summer/weekend car. When he stored it, he stored it right.

A few months after I bought it (and continued running Mobil 1) it crapped out and had no compression. I feel it was because the teflon in the synthetic wasn't burning. I noticed around the first oil change that I hadn't lost any oil like I'm supposed to. So I think that the passages clogged up.

Maybe you can shine some light on why it crapped out. I'm still convinced that the synthetic didn't burn right.

Rotarykid7

belive me i tell him all the time, anyway thanks for the info.

btw your wiper relay works great!

trent1059

It's my money and I like the superior protection that synthetics afford. I use royal purple,genuine mazda oil filters and have my oil changed every 1500 miles, overkill? yes, but once again it's my money and my car...I like it

Evil Aviator

Oh absolutely. I have wasted all kinds of money on my car, too, lol. However, if you add up the extra cost of the synthetic oil, especially at the unnecessarily short change duration that you have chosen, the insignificant amount of extra protection on a street car simply does not make up for the extra cost. Here is the price breakdown based on your current situation:

Your oil change = Every 1,500 miles

Mazda recommendations for "unique" driving conditions:
Turbo II oil change = Every 3,000 miles
NA FC oil change = Every 5,000 miles

Typical FC engine lasts about 150,000 miles before a rebuild.

150,000 / 1,500 = 100 oil changes per your car
150,000 / 3,000 = 50 oil changes per TII engine
150,000 / 5,000 = 30 oil changes per NA engine

Estimated oil change for your car = 5.5 qts
Typical TII oil change = 5.5 qts
Typical NA oil change = 6.5 qts (one qt added for normal burn-off at 3,000 miles)

100 * 5.5 qts = 550 qts oil for the life of your engine
50 * 5.5 qts = 275 qts oil for the life of a TII engine
30 * 6.5 qts = 195 qts oil for the life of an NA engine

Now multiply the qts of oil for your engine times the price you pay per quart.

Example:
Your engine using Royal Purple @ $5/qt = 550 * $5 = $2,750 of oil costs per engine.

Compare to an NA at normal change intervals using Castrol GTX @ $2/qt = 195 * $2 = $390.

The difference between Royal Purple and Castrol GTX is $2,750 - $390 = $2,360, which just happens to be about the price of a professional 13B rebuild plus street porting. While I am sure you are happy thinking that the synthetic oil is protecting your engine better, I will take the free engine rebuild with street porting with MY money.

rcjunkie

The superior protection that synthetics offer would not help in a typical rotary engine used as a daily driver.

Synthetics are typically superior in not breaking down at high temperatures and offer better flow during a cold weather start. Your engine will blow before you realize the benefit of the oil not breaking down at high temps and improved cold flow can be accomplished with a 10w-30 weight oil in the winter.

The PRIMARY advantage of a synthetic oil is EXTENDED OIL CHANGE INTERVALS. In my piston engines I'm getting anywhere from 10,000-12,0000 miles out of my synthetic oil. How long my oil lasts is dicated by an oil analysis laboratory but I typically run it for 250 hours before I change it

However, since our rotary engines are injected, I prefer to change my oil sooner. My oil is changed every 100 hours and my interval varies anywhere from 3,000 miles to 5,000 miles.

If you do want the best non-true synthetic grade oil, here below are a few recommendations. Note, many of these oils are advertised as synthetic but actually are Group III base stock oils. True synthetics are considered to be Group IV (PA0) or Group V (Ester) base stock oils. Castrol Syntec is a Group III base stock oil and was sued by Mobil 1 for calling Syntec a synthetic. Unfortunatley, Castrol had better lawyers and won the case. Castrol Syntec sells their oil at Group IV and Group V oil prices even though it is a cheaper Group III base stock oil and is taking advantage of consumers. Group III basestocks are nothing more than severely hydrocracked crude oil. Group III basestock oils do offer better performance and protection against engine wear then Group I and Group II oils (your normal non-synthetic oils).

Here are my recommendations for Group III oils:

1. Shell Rotella T 5W-40 oil. This is an excellent oil that is a Group III oil that can be bought for 12 dollars a gallon at Wally World.

2. Castrol Syntec is also a Group III oil but unlike Shell Rotella T, costs 2-3 times more.

3. Any synthetic brand other than Royal Purple, Redline, Mobil 1, Amsoil are typically Group III oils and can be used in your engine. (the true synthetics can also be used but their use is not cost effective)

therotaryrocket

i'm pretty sure i've seen alot of rotary engines over 300,000 miles, one with like 450,000 miles with the original engine, this is from good maintanence so maybe that more expensive oil and change intervals you speak of would be a little more money saved if your engine does live twice that of a typical one, i think a typical one using dino oils if properly maintained will last atleast 300,000 miles. well anyways, icemark you say that synthetic oil does burn well? mazda doesn't suggest it for any rotary, why is this? i hate telling myths, transferring false information and i appreciate the enlightment.

wthdidusay82

iTrader: (15)

My car had 146,000 when it blew, i guess it was just overheated cuz one of the irons coolant passages was blown out

im hoping to get another 75,000 miles out of it from mthe rebuild or at least 2-3 years or whenever i sell it...of course im going to maintain it will and do oil changes every 1500-2000 miles using castrol gtx

rcjunkie

THERE IS NO TEFLON IN MOBIL 1 OR ANY OTHER MAJOR BRAND OF SYNTHETIC OIL. Where in the world did you get this bad information? TEFLON is not an approved oil additive per DUPONT's, the manufacturer of TEFLON.
If you weren't burning oil, it sounds like your oil metering pump crapped out on you. Don't blame Mobil 1.

88 GTU

the way i switch to synthetic is do a regular oil change and use mobil 10w-40 then drive it for a few weeks because mobil is a detergent oil so it's cleaning it then i do another oil change and use mobil 1 mobil 1 is fine i've used it in my car for 3 years now and i drive it hard and about a month ago i figured i'd do a compression test and the car had not run for 3 weeks and i got 90-90-90-115 front and 90-90-90-115 rear thats with 101k miles

Mason Rx7

That was what I was looking for. Do you work for a oil company or something?

Haha! If my oil pump had crapped out wouldn't I have lost oil pressure?

Digi7ech

iTrader: (1)

I was using Regular Dino oil for a while.

During Sevenstock I switched over to Royal purple.
Seemed to be a little better. Gave a bit more psi and clung to **** like a ****! Also helped slow a few leaks down.

About 3 weeks ago my car decided to have an emergency evacuation of all oil on the highway. Well on a Sunday the only RP supplier wasn't open. So I just got some regular dino oil again.

Runs just fine with either oil.
I think running synth vs regular doesn't do a whole lot with our cars.
The more major thing would be premixing.

Premix is a a higher level than the stock OMP system. ANy body which has pulled an engine apart has seen the OMP injection hole in the housing. Don't tell me that that hole with no pressure behind it actually does anything.

BTW. The Synth in rotaries myth was debunked by companies like RP.
Regular dino oil actually burns worse in an engine than Royal purple does(even though neither is meant to be burned).

That's why Premix is soo much better. It' s a lubricant meant to be burned.

Rotarykid7

evil aviator that was awesome...and good info, never took the time to think about it that indepth!

Icemark

No, the primary advantage of a synthetic in a rotary engine is the minor decrease in friction faces.

Synthetics should never ever be used to exceed the factory recommended oil change intervals. Yes, the Synthtic does not break down as earliy as conventional oils do, but the partiulate level still builds up.

NO NO NO NO.

It has been proven in independent lab oil testing that 5W40 (and conventional 10W40, and conventional 10W50) oils as well as Castorl Syntec, have a radically increased amount of ash (what is left when the oil is burned) which will leave deposits on the rotary faces, and also have above normal and elevated levels of Zinc (normally an anti-wear additive in most oils) which will also lead to deposits on rotor faces and sparkplugs.

The ONLY safe synthetics (as posted only about a billion times here) are Royal Purple, Redline, Mobil1, Neo, Amsoil. Other synthtics do lead to increased ash and deposits in Rotary and piston engines when burned.

Which leads to therotaryrockets question on why Mazda does not recommed synthetic oils in rotaries. (Again posted only about a billion times here) its because Mazda couldn't say it was safe to use Castrol GTX and say that it was not safe to use Castrol Syntec. They couldn't say one brand was okay, but another was not.