What is usually best for rotaries?... synthetic or natural? I'm not sure because someone said something about Mobile 1 and that got me to wondering. Is it good/bad to use synthetic?

 

Bad, The synthetic oil does not burn well if at all!

 

Have a search through the archives. Huge amount of conjecture and repetion of old wives tales to be found

Bottom line is that noone I am aware of has ever had problems running synthetic. It will also give you a few more HP as friction is very high inside a rotary, but only a few. On the other hand if you change you oil regularly then regular should be fine.

Anyone who says it doesn't burn cleanly is generally just regurgating what they read on a website. I have seen NO evidence that modern synthetics burn any less well than dino oil.

So do what you feel happy with.

 

What oil should I use?

--Bob

 

Run the synthetic after the engine is broken in and also use a touch of MMO which I believe acts as a catalyst to break the synthetic oil polymer in the combustion chamber side of the housings....who actually out there has lost an engine to synthetic oil personally? Exactly.

 

I've used Castrol dino oil for years, but thinking about switching to Amsoil after I get this T2 engine broken in.

 

Aright... I am currently running with Pennzoil and my dad said it'd be a good idea to ask you guys about synthetic. Next oil change I'll try out mobile 1...(I think synthentic is generally cheaper??)

 

I have always used castrol 10/40 in the winter and 20/50 in the summer. I picked it due to some oil data info on diffferent oils and there prop, amsoils had the best data with castrol being the second as far as natural oils. The guy at rotery perfomance told me you can use synthetic but will have to change the plugs more ofter since it does not burn the same as natural oil, he also told me to never use castrol synthetic on my car though, I cannot remeber why. I will try to fine the oil info sheet I had and post it.

 

p.s. I do use mobil 1 gear oil in my trans and my rear end. as well as synthetic brake fluid.

 

I was wondering if any of that about synthetic not working was true or not, I'll just have to try it out myself I guess.

 

Oh really? Well thanks in advance if you can post it. The last thing I want to do is mess up my new car with the wrong oil.

 

from what the rx7 guy told me it that it work and he uses it on his 645 hp 93 race car , he just has to change the spark plugs more often

 

I run 15w-50 synthetic Mobil 1 in my mainly AutoX 82. of course I have also removed the OMP and run pre-mix....

 

here it is.

Brand VI Flash Pour %ash %zinc

20W-50
AMSOIL 136 482 -38 <.5 ---
Castrol GTX 122 440 -15 .85 .12
Exxon High Performance 119 419 -13 .70 .11
Havoline Formula 3 125 465 -30 1.0 ---
Kendall GT-1 129 390 -25 1.0 .16
Pennzoil GT Perf. 120 460 -10 .9 ---
Quaker State Dlx. 155 430 -25 .9 ---
Red Line 150 503 -49 --- ---
Shell Truck Guard 130 450 -15 1.0 .15
Spectro Golden 4 174 440 -35 --- .15
Spectro Golden M.G. 174 440 -35 --- .13
Unocal 121 432 -11 .74 .12
Valvoline All Climate 125 430 -10 1.0 .11
Valvoline Turbo 140 440 -10 .99 .13
Valvoline Race 140 425 -10 1.2 .20
Valvoline Synthetic 146 465 -40 <1.5 .12

20W-40
Castrol Multi-Grade 110 440 -15 .85 .12
Quaker State 121 415 -15 .9 ---

15W-50
Chevron 204 415 -18 .96 .11
Mobil 1 170 470 -55 --- ---
Mystic JT8 144 420 -20 1.7 .15
Red Line 152 503 -49 --- ---

5W-50
Castrol Syntec 180 437 -45 1.2 .10 .095 % Phosphor
Quaker State Synquest 173 457 -76 --- ---
Pennzoil Performax 176 --- -69 --- ---

5W-40
Havoline 170 450 -40 1.4 ---

15W-40
AMSOIL 135 460 -38 <.5 ---
Castrol 134 415 -15 1.3 .14
Chevron Delo 400 136 421 -27 1.0 ---
Exxon XD3 --- 417 -11 .9 .14
Exxon XD3 Extra 135 399 -11 .95 .13
Kendall GT-1 135 410 -25 1.0 .16
Mystic JT8 142 440 -20 1.7 .15
Red Line 149 495 -40 --- ---
Shell Rotella w/XLA 146 410 -25 1.0 .13
Valvoline All Fleet 140 --- -10 1.0 .15
Valvoline Turbo 140 420 -10 .99 .13

10W-30
AMSOIL 142 480 -70 <.5 ---
Castrol GTX 140 415 -33 .85 .12
Chevron Supreme 150 401 -26 .96 .11
Exxon Superflo Hi Perf 135 392 -22 .70 .11
Exxon Superflo Supreme 133 400 -31 .85 .13
Havoline Formula 3 139 430 -30 1.0 ---
Kendall GT-1 139 390 -25 1.0 .16
Mobil 1 160 450 -65 --- ---
Pennzoil PLZ Turbo 140 410 -27 1.0 ---
Quaker State 156 410 -30 .9 ---
Red Line 139 475 -40 --- ---
Shell Fire and Ice 155 410 -35 .9 .12
Shell Super 2000 155 410 -35 1.0 .13
Shell Truck Guard 155 405 -35 1.0 .15
Spectro Golden M.G. 175 405 -40 --- ---
Unocal Super 153 428 -33 .92 .12
Valvoline All Climate 130 410 -26 1.0 .11
Valvoline Turbo 135 410 -26 .99 .13
Valvoline Race 130 410 -26 1.2 .20
Valvoline Synthetic 140 450 -40 <1.5 .12

5W-30
AMSOIL 168 480 -76 <.5 ---
Castrol GTX 156 400 -35 .80 .12
Chevron Supreme 202? 354 -46 .96 .11
Chevron Supreme Synt. 165 446 -72 1.1 .12
Exxon Superflow HP 148 392 -22 .70 .11
Havoline Formula 3 158 420 -40 1.0 ---
Mobil 1 165 445 -65 --- ---
Mystic JT8 161 390 -25 .95 .1
Quaker State 165 405 -35 .9 ---
Red Line 151 455 -49 --- ---
Shell Fire and Ice 167 405 -35 .9 .12
Unocal 151 414 -33 .81 .12
Valvoline All Climate 135 405 -40 1.0 .11
Valvoline Turbo 158 405 -40 .99 .13
Valvoline Synthetic 160 435 -40 <1.5 .12

 

or here is the link
http://auto.howstuffworks.com/framed...-overview.html

 

I used this exact information in choosing my oil - only I picked Havoline over Castrol. Havline has a higher flashpoint and higher zinc content, both of which (IMO), are critical in high temp rotory engine. I've been using Havoline now for 3 years and find tht I'm burning less oil (and I don't mean consumption through the OMP) - both my '83 and '85 required less topping up - whether that's due to Havolines higher flashpoint would be tough to prove but I'm betting on it

 

FWIW, I corresponded with several large oil companies and asked them to endorse the use of their synthetic range in an FB.

They all recommended their semi-synthetic and said it would burn cleaner than mineral in a street setup.

The fully synthetic range they only recommended in race engines that constantly run at high RPM as the heat prevents residue buildup.

So if you trust the words of oil company techos you could go by that.... Of course they could just be repeating what they've been told too

..Matt

 

What does having more zinc content do??

 

Who knows about the zinc? But, synthetics are always more expensive. The companies making them will tell you it's only marginally more expensive because you can go three times as many miles before an oil change, but if you're in the habit of changing it every 3,000, it gets hard to try that after you see the odo roll past 5,000 and you haven't changed the oil yet. I used to rationalize to myself that the engine was burning some of the oil off, so it wasn't all the same oil I put in there 5,000 miles ago!

 

Read the "Oil" article that was attached earlier in this thread. It's supposed to protect the motor against metal on metal contact - they also say it causes plug fouling but i haven't noticed any
Just thought I'd mention it although the flashpoint was my major point

 

OK.