with engines with high temps why have i heard of useing a 40 weight oil

 

40 weight oil is a thicker or a higher viscosity oil. See chart for rating system.

All oils thin more and more as they get hotter and hotter (eve with VII's, they still get thinner, just not as fast). If you run your oil temperatures hotter than normal operating conditions due to climate, racing, etc, a thicker oil will provide better protection at these very high temperatures because it will not thin down below acceptable protection viscosities.

High Temperature High Shear (HTHS) is a standard oil test to measure these extreme conditions. Normally a 40 weight oil will not get below 3.7cSt in this test while a 30 weight will get down to 3.0cSt or so.

20 weights will get even thinner under these conditions and this is why many recommend a higher viscosity oil than a 20 weight for the 8 - to assure protection in these extreme situations in which the rotary can sometimes find itself.

 

thank you for your response very helpfull what do you think of running 0-30w mobile one during the winter times compared to the 10-40w during the summer times

 

Generally, that is a good approach, but you have not shown your location, which could alter that somewhat.

If you are in the Southern US, you could run a 40 all the time. Mid US, the approach you are taking is good. Northern US/Canada, a 20 Winter/30 Summer might be good.

Of course, many use a 20 weight year-round not matter where they are, and this is fine in you are not in a very hot climate, racing, extreme city driving, etc that could causes sustained high oil temps.

On the M1 as your oil choice - a fine oil, but some are leery of it for the rotary as it has a bad history, as it seems to generate more deposits when injected/burned in the combustion chamber. It is stated that M1 is the reason Mazda does not recommend synthetics.

Not to get into another dino/synthetic debate, but I think synthetics in general are fine, but might shy away from M1.

I personally am using the new CJ-4 Shell Rotella T Synthetic (RTS) 5W40, and am very happy with it. It is an Heavy Duty Engine Oil (HDEO), designed for diesels but compatible for gas engines as well, which has a much stronger additive package that Passenger Car Motor Oils (PCMO) as it has more anti-wear ingredients (primarily ZDDP) than PCMO oil standards allow and has more dispersants/detergents to better deal with all the carbon a rotary generates.

There are two other Very good HDEO out there as well, Delvac (Mobil) and Delo (Chevron). Any of the 3 major HDEO brands would serve you well and make dino and synthetic versions. If you are shy about the synthetic, all three brands make a 15W40 dino version that are very good oils - and Rotella even makes a 10W30 HDEO.

 

Its kinda pointless to change oils for the winter/summer, because the oils are engineered for that reason. You could run a 0w-30 all year, or 0w-40 all year.

 

i live in missouri and it is 105 today and gets in the low teens in the winter. were can i pick up the 5-40w that you were speaking of

 

Rotella T Synthetic (RTS) 5W40 is available at Wal-Mart for around $18/gallon - very good price on a great oil. It is also available at most parts stores, but likely not as inexpensive.

BTW - Rotella T Dino 15W40 can be had at WM for about $9-10/gallon - still a very good oil for a great price - but in Missouri may not want to use in the 3 winter months.

 

It's like 68 degf here today. 5w-20 is plenty.

I do like Mobile1 in the winter in my Jeep tho'. Cold cranking is facilitated by its enhanced viscosity/lubricity.

 

Sure it is champ. 0W-30/40 is a MAGIC oil that does all things better than all other oils. All other viscosities are just "marketing" gimmicks.

 

yeah the hotter the weather or hotter you are making your engine/oil from racing/city driving etc the thickeer the oil the more protection it is....20 wt in 200 degree weather will be twice as this as a 40wt hence sticks to parts more and protects better

 

The guy said what he was running...not me genius. If the guy wants to run 0w-30, he can do it all year long. The outside temp is only an issue when its cold....hence the cold temp rating listed. If the engine runs at 210 degrees when its 10 degrees outside....its not gunna run 300 degrees when its 90 degrees outside. Operating temps will be nearly identical. So before you try to make someone look bad, at least have a clue.

BTW, reply all you want with dumbass theories on why I am wrong. No need to ruin the guys thread, I am done.

 

I bet there's no need for me to reply, don't want you looking bad.

Maybe you should read up before you talk trash because if that's the extent of your reason and logic about lubricants, then you have no place commenting about it.

Go READ https://www.rx8club.com/series-i-tech-garage-22/oil-technical-145817/