sirkus

I was told by someone that if I put Synthetic oil in my car... it doesn't work to well... is this true? can it mess up my motor? because i ran out of 10W-40 non synthetic so i just poured a quart of synthetic in there. thanks for any help.
eric

MtnRacer

You're going to get SO many different answers on this subject that it will be near impossible to get a general consensus. But here's the situation as I see it.

The general complaint against synthetic motor oil is that it has a higher flashpoint than non-synthetic oils. This means it's not going burn clean in the engine, and it will leave all sorts of deposits on your housings. Pro-synthetic guys claim that this is not the case, and that the newer synthetics won't cause this problem. My take is that you should be changing your oil SO OFTEN, that it doens't matter whether you put synthetic in or not, because before it even has a chance to do it's real job(superior lubrication of every other moving part in the engine) you're going to replace it with a fresh resevoir of oil. What I'm trying to say is: You should be replacing your oil too often for synthetic to make any sort of difference. For this reason, I think there's no point in putting in synthetic, and would recommend just plain old motor oil.

Steve

P.S. The synthetic you just put in there probably won't hurt the motor much, but I wouldn't make a habit of it, "just in case."

kleetuz

iTrader: (2)

I don't think you are supposed to mix synthetic and non-synthetic oils...

MtnRacer

That's an old wives tale.

Steve

Blowtus

don't mix oils, the additives are designed specifically for the formula provided, and mixing synthetic with mineral is probably no good either. Don't stress about your motor. Just use mineral next time.

Charlie

OC_

You know synthetic oil is just better then non. Thats why they say not to use it on a new (piston) engine, since its so slippery the engine cant break in! It doesnt matter if you change you non synthetic oil ever 10 miles, synthetic oil is just superior.
Im going to install a seprate oil resivor for the oil injectors, theres a kit for that and you can fill the reservoir with clean burnin' 2 stroke oil. Then i can run any synthetic oil i want in the 'crank case' with no worrys!

Ryde _Or_Die

All I know is I put some 10w-40 in when I didn't have any 20w-50 and it made smoke out of the exhaust. I changed the oil with 20w-50 and the smoke went away.

As for synthetic goes, Racing Beat recommends Royal Purple synthetic so it has to be ok by my standards.

Icemark

been covered thousands of times....

but overall, a good brand synthetic like Royal purple, Neo, Castrol, or Redline should be perfectly fine and actually provide a slight increase in HP (about 1 to 2%).

But poor quality synthetics such as Valvoline, Exxon, Pennsoil, Havoline, and several others are not formulated for the higher temps of the rotary, and the reduced ash and deposits that are required and should not be used in any high reving engine.

The draw back is the cost. Other than minor HP increases when using the better quality synthetics there is no advantage in less engine wear or oil durabilty over conventional oils. So they are seldom cost effective unless that extra bit of HP is required in a high performance application not seen in 90% of the owners out there.

Furthermore just like a conventional oil, anytime the rotary engine is flooded; the oil and oil filter must be changed in a rotary which can be very costly.

jeremy

iTrader: (1)

your motor is going to pop.

LT1-10AE

I'll throw my $.02 in.

It may have just been a freak coincidence, but I went to get oil & filter for my GTU one day and Pep Boys was OUT of Castrol 20w50(!)

Looking around, I saw Castrol Synthetic. I said, what the hell, I'll give it a shot. I changed the oil that Sunday and everything was a-ok until Wednesday. I didn't drive the car hard at all that day. I stopped in at a store for about half an hour. When I came out to start the car, it spun about three times, then locked solid. I figured carbon lock.

I put it in 5th, rocked it back and forth a few times and it wouldn't budge. Had it towed home and several of us got on it rocking it back and forth - it finally gave in.

I had broken an apex seal clean in half on the front rotor. Apparently the seal was snapped, and pushed out by the springs into the exhaust port, thereby locking the engine.

Was this caused by buildup of unburnt synthetic oil? I kind of doubt it. Did it spook me that the apex seal took a dump just DAYS after changing the oil? Yup.

I haven't heard anyone complain about using Castrol or Havoline dino oil, but I have heard quite a few dislike synthetic for one reason or another. I'm going to stick with the masses and stay with dino.

GR8PIPES

The lube and oil shop talked me into putting Chevron synthetic oil in my 89 RX-7 conv. Within a day I started blowing smoke out the exhaust and using about a quart off oil per 100 miles. I changed back to 20/50 mineral oil but it’s still burning a quart per 100 miles. Now I'm told I’ll need an o-ring and might as well go ahead with a full rebuild of the engine. Call it coincidence but I regret doing it.

Detriuch

iTrader: (1)

yea dont put synthetic in with your car in the stock form. wont run to well.

sirkus

thanks for all the help. I went and got a oil change back to my normal 10w-40. I just won't put anymore syn. in there anymore. thanks.

ZachSpazz

I'm quite wary of using synthetic oil in a rotary. The only way I'd consider it, is if I wasn't running the OMP and had quality 2-cycle in the gas. At that point, the engine's combustion surfaces don't see any synthetic oil and thusly the risk of excess carbon build up is lessened. Synthetic oil is wonderful stuff and can only be a good thing on the inside of the rotors. The method of cooling the inside of the rotors is very hard on oil and synthetic has properties that are better suited for this harsh environment. However, Castrol GTX is just dandy and is cheap as well.

For what it's worth.

RETed

My 2 cents...

We've found engines running synth (specifically Amsoil 20W50) develop significant deposits on the rotor housing, over engines running dino juice.&nbsp These deposits can lead to poor performance and possible premature apex seal damage.

If you absolutely have to use synth, like in the case of the original post - go for it.

But, for cars running stock oil injection, I wouldn't keep running it.

For those who are running into increased smoking problems, synth typically shrinks oil seals.&nbsp This means synth oils tends to "blow by" these seals the previously sealed dino juice with no problem.&nbsp Changing back to dino juice tends to swell these oil seals back to "normal" given a little time.&nbsp I've also heard that synth oil molecules are typically smaller than dino juice molecules, therefore, synth tends to "blow-by" and leak more on an engine that was previously using dino juice.



-Ted

jdmfdrx7

Ok now here is a question. What do you guys think about those type of oils formulated for high millage engines? I have a higher millage engine and was wondering if those might be any better then plain dino oil?

RETed

You really should not get lazy with the oil change interval.&nbsp The rotary engine is very sensitive to oil quality.&nbsp Changing oil every 3,000 miles is very good preventative maintenance, and your car will love you back for it.

Those high-miles oils just have added additives that are of no use in a rotary engine.



-Ted

jdmfdrx7

umm I dont think I said anything about being lazy, in fact it would be just the opposite if anything. I change my oil usally between 2000 and 2500 miles, so it would be nice it you would not make generalizations and flame me based on a simple question I asked. My car has 117k miles and I just wanted to know if those types of oils might benifit me at all.

God Forgive me for asking people for there opinions.

RETed

My bad - I got "high mileage" and "extended interval" all mixed up.
Geez, don't get your panties in a bunch, it was my fault.


-Ted

jdmfdrx7

~thanks abunch

dr0x

The problem with using synthetic on a old motor is it can move a lot of crude around from the old mineral oils, which can cause leaks etc. Not only that, like someone else mentioned if you flood the car it needs to be changed out, can get kind of expensive.