I use 10w-40 year round. Anything thinner and my car will eat about a quart a week. That's my two cent's. Then again the last owner of my car never changed the oil and I guess that is why it blew the motor at 68k. But that car is gone now my Turbo II is waiting for me at home.

 

I use 20-50W and it seems to eat less over 5-30. Or it could be I am just nutz. Anyways here in good old florida the thicker the better.

 

i use 5w-25, i think, oh well **** it

im going to start using Crisco or some ****

 

crisco lol

 

I read somewhere that Mobil 1 10w30 has the same viscosity as a mineral oil 20w50. True?

~Jeremy

 

For my car, I'm thinking of running a 10W-40... 'cause my car may see some low temp starts... but It shouldn't be below -15 Celcius... It may be run in temperatures up to 35 - 40 Celcius... Is this gonna run too thin? Should I run a 20W-50?

 

I called mazda and they said that they use 5w30 here in KC, MO.
so Is it BETTER to use thinner oil for regular street driving or use thicker oil?

which one burns cleanly?

 

Ok... I've decided to go with the 20W-50... I decided this because I'm gonna be running some MMO in the oil... so I don't want to run it too thin...

 

Never trust what the dealer tells you about a RX-7. After the warrenty period they want your car to break down so you will bring it in and pay them to fix it.

once again oil:

Average starting running temp:

under 0F: 5W30
Under 30F: 10W30
above 20F: 20W50 (or 15W50)

*edit
This stuff is posted under the hood, and in the shop and owners manuals. Doesn't anyone read them?
*end edit

Avoid 10W40 and 10W50 as there are too many additives to get thet range of viscosity. These additives will have a higher ash content than other oils.

Higher ash= more deposits.

 

make sense,
thanks icemark

 

castrol 20/50 all the way....nothing better in my opinion.....and being in south Fl have to use it year round......sometimes i alternate between the synthetic blend and regular....never had any problems in any of cars that i have owned....

 

Ive only changed my oil once since my purchase but I am gonna start using 10w-30.

 

Hey Icemark, you forget to mention one thing in our previous debate, flooding. It would've ended the other thread very quickly.
Gas thins oil big time. I personally hate the use of thick oils like 20w50 because there is no proof that it benefits the engines. None zippo nada. Don't quote oil company facts like some researchers do. If you wan't facts, just send the oil in for a test. $20 buys a test. $10 buys a filter & 5 quarts oil. Guess what I do

http://www.oaitesting.com/ http://youroil.net/index.html http://www.analystsinc.com/services/...l_analysis.htm http://www.blackstone-labs.com/ http://www.oilanalysis.com/ http://www.practicingoilanalysis.com/ http://www.oillab.com/

Because of all the flooding issues that people experience, maybe the 15-20w40-50 is very justifiable. Especially since noone mentions that they change their oil frequently enough(3000miles isn't) or right after a flooding episode. Logically, gas will thin the 5w30 much quicker than the 20w50. Gas isn't known as a great lubricant One flood should force an instant oil change.
Since my car doesn't flood anymore, I usually stick with 10-30 or 10-40 depending what is on sale/marked down/ or comes with a rebate. Oil shouldn't compete with the beer budget.
With a couple of flooding episodes that my Rx7 suffered(due to varous sensor failures), the 5w30 and 10w30 oils looked like ....you know ....when you're standing over the toilet.

Too bad CR http://www.xs11.com/stories/croil96.shtml didn't toss in 20w50 in there Taxi test. Even though I hate CR(concerning autos), read what they say concerning the socalled "popular belief." You'll have to read the whole article.

These guys like to waste money on tests instead of change intervals. Very interesting to look through all the comments, mileage intervals, viscosity change with miles, etc....
Download the .pdf from here and read it:
http://forums.maxima.org/showthread.php?threadid=100060

And concerning the owners manual, read it but don't forget that the manual was written 15 years ago using the technology that was available 15 years ago. Good luck finding an SF oil that the manual mentions since SL is for 2001 and newer vehicle Damnit!
When is the Rx8 coming out? I've been using the wrong oil since 1993 after the release of SG. The owners manual didn't tell me that it superceded the SF Wheres the TSP, like other auto manufactures have, that says anything over SF is good. And before anyone says that SL supersedes everything before it, than why doesn't GL6 supersede GL5 which doesn't supersede GL4?

The api website doesn't evenlist the SL. Talk about being up to date.
http://www.api.org/programs_services...y/oilguide.pdf
Its funny that the local gas station does:
http://www.burkeoil.com/pdf/oilguide.pdf

Anyone want to put a quart of 20w50 in their freezer and see what it looks like at 20F? It 90F out right now and I just changed the oil in my dads car. I used 20w50 because of a little drip on the driveway that the car left. His engine clatters like mad now. The oil pressure is great(actually better) but the noise is unbearable. Sure, it isn't a rotary and doesn't have the drip anymore. But, wheres all that thick oil's protection? I guess that oil volume is more important than oil pressure which is usually more important than oil viscosity.

 

On your dads car what does the factory call for, on an oil... chattering to me suggests a OHC or OHV engine...but when was the motor designed??? what application is it being used in???

I really believe it is specific to the engine design, hence when the series 4 engine or my old early '80s RA64 Celica 22R motors were designed around 20 years ago the 20W50 was the best oil for high temp applications. Heck as a side bar, I am sure you remember even some Oil manufactures called their 20W50 weight oils "Turbo" or "Turbo safe". But the engine manufactures still figured that a certin viscosity must be maintained and designed the engine for that visosity. For that amount of oil.

Now jump ahead 15 years, and look at cars like my DOHC V8 SC400 or DOHC V6 Tacoma. Block, Valve and ring materials have jumped a trifold in tolerances and strength. A lighter weight oil can (and should) be used, because there are tighter tolerances. A thicker oil (like a 20W50 or even a 10W40) in these engines will cause the loss of HP and mileage (both very important to the US market). But the engine were designed for it. Unlike most of our FCs.

So if the vehicle manufacture calls for a 10W30 or and 20W50 at your low temp of the day... I feel it should be used, for that is what the motor is designed for.

Oh and getting back to your comment on:
I think maybe you are misunderstanding the SL or SF or whatever ratings in motor oil. They are simply a purity test. They really have little bearing on oil ratings other than if you have an old quart of SF grade oil laying around you shouldn't use it in a newer SG rated engine. Again it gets back to tolerances and what the engine was designed for, but in this case for amount of foriegn particles floating in the oil but in the case of some of the newer grades it also covers the latest industry requirements for protection against deposits, wear, oxidation, and corrosion. A higher grade always supplants a lower grade.

It is not like the GL ratings or DOT # ratings at all.

 

S-classifications is not a purity test. It is a performance test. That is one reason why the oil today is superior to the oil of yesteryear and why we do not need heavy viscosities to protect engines like we always did before.
S-classifications test measure engine wear(protection), sludge/acid control/particle control(oxidation/detergents/dispersants), and heat stability(todays tighter/hotter enviro happy engines). I purposely mentioned classification comparisons for people to think a little and research on their own. I also have little fate in the oil classifications provided by SAE, API, ILSAC, NMMA etc. Some of the testing that we used is flawed. But, if its good enough for a star/weight/acronym, then its good enough for the consumer/auto manufacturer. $.15 worth of oil that we get charged $1.50 for.

Tolerances? What is so different between the tolerances of an 1989 rotary and a 1991 rotary? Mazda doesn't list anything but 5/30 and 10/30 in the 1991FSM compared to the 1989FSM which also lists the 10/40 10/50 and 20/50. Did the engine change much? No. Did the oil change? Yes. It went for SF to SG and now SL.

My dads car can use 20/50 for the summer. And, with 200,000+ miles, I can only imagine what the bearing/crank/cam clearances are. But it sounds and runs like ****. He's gonna have to live with the leak. 10/40 is going back in before it gets cold.

And if the owners manual is godlike, remember to follow its unflood the "CYLINDERS" procedure. It is a generic book written with the technology available.

And in the previous thread, Amsoils test proved that the thin oils at temperature, under pressure, provide as much protection or better than the thicker oils. I haven't seen any PROOF, however biased, that thick oils are superior to thin oils. None, nada, zippo!

 

10w-30 for me

 

5w-30 is what I use but after reading the posts I might change that.

As someone mentioned above---do change your oil after a flooding episode. I had my car painted last week and even after warning the guys at the shop and writing a note and taping it to the steering wheel, they flooded it out anyway.

They did get it started again because it was running when I go there to pick it up. When I saw the smoke from the exhaust, I knew it had been flooded. I drove it home and checked the oil. It smelled just like gas. I changed it right then and there and it came out just like it was water. Just my $.02. Keep the change.

BTW--as I am a proud papa of my new paintjob, please feel free to check it out:

http://www.carolinalights.com/php-bi...album06&page=1

 

I'm so surprised the merits of Synthetic vs Regular oil has been discussed.

Icemark, DeadRX7Conv, stiltner.... you two seem to have done the most homework on this subject.

Care to share you thoughts as it relates to Synthetics??

 

Synthetics rule. But some say that synths do not burn well in the rotary. It may cause carbon buildup in the engine oil injected engine. With the extremely high heat of combustion in the rotary, I can't see why it would be a problem. But, if there is one engine failure out there somewhere that used/blamed synthetics, then it may not be worth the risk. Then of course, how many apexseal/carbon/oil related engine failures are there with dino oil??? Everyone elses!!

If you eliminated the MOP/OMP and run premix, use synthetic.
If you use the oil metering pump and have enough money saved for the rebuild, give it a shot. If you don't experience problems. Share the info.
My last 3 oil changes had a 1 quart blend of Mobil1 5/30. I have no carbon issues on the spark plugs and the engine runs great. I change my oil frequently(every 2000 miles). If I were to run 100% synthetic, the added maintenance cost would exceed my "fun car budget". Plus, my synthetic is usually free. Its the leftover from oil changes when 6-quart cases of synth are bought. Not too many cars use 6 quarts of oil.

My mom's/dad's/sister's/brothers'/inlaws' & my cars/motorcycles/lawnmowers have run synthetics for almost 20 years now. Noone in my family has every had an oil/ATF/gearoil related breakdown/repair. Thats about 2-million miles with every make model vehicle type imaginable. I can't say that for my customers/neighbors/friends who used dino exclusively.

 

I have actually three thoughts on Synth oils.

#1 Most synthetic oils have an almost identical burn temp to conventional motor oils and all of them around 400F. There should be little if any carbon/ash/build up issues as the ash content is typically lower than most conventional oils. So based on that there really isn't any reason not to use synthetic oils after proper break in except:

#2 the cost of a synthetic oil is still radically higher than a conventional oil, with no real benifits if following the under 5k mile oil changes that most people (including myself) recommend on rotary engines.

and

#3 that although synthetic oils are supposed to be slightly more slippery than conventional oils, I have not seen any engine performance gains that can be verified. The other draw back to more slippery is the tendency of the synthetic oils to slip past slightly worn engine seals and gaskets, creating oil leaks where there was no apparent leaks before.

 

Racing Beat actually claims noted performance improvement on the Dyno with Royal Purple Synthetic motor oil.

As I posted a couple weeks ago, I decided to go with Royal Purple in my Diff. Racing Beat is near me so I bought it there. And, in general conversation the above was mentioned.

With your excellent understanding on this subject, it would be interesting to hear you comments on this after talking to Jim or whoever at Racing Beat.

 

Yeah I need to talk to Jim to see what they really got, but what performance increase did they see??? 1 or 2 HP and a couple of Ft/lbs??? or was it sizeable??? Or was it that the engines just run a bit cooler???

It would have to be 5 or more HP to break even IMO for the additional cost.

 

If it's over 5 hp gain, PM me that report so I can go stock up before the Forum stampeeds to buy it up.

 

If they seen ANY improvement by just using different oil, I think that's pretty good, don't you?

 

this isn't about Royal Purple Diff oil.

It's about Royal Purple engine oil.