Correlation #1:
Phoenix, Arizona is hot. Very hot.
When I came here, I was still using the recommended 5w-20 viscosity oil (Mobil 1).
That stuff would turn to water on a 105°F day, so I started thinking about the effects of a heavier oil.

After a few months of being in Phoenix, my idle vacuum stabilized at -52 kPa once the car was warm. Though this is on the low-side, it is still acceptable.
Last week I switched to 10w-30 Mobil 1. After that, my idle vacuum was stable at -56 kPa.
Conclusion - higher oil viscosity produced better sealing.

Correlation #2:
I just completed an 1100 mile round-trip to Buttonwillow CA and back. That is 1100 miles in two days, most of which was realized at 85 MPH and above. An interesting stretch of that trip was the section just north of Los Angeles where we climbed about 4500 feet in just a few miles. This was done in 6th gear and 90 MPH or greater. As you might deduce, I was in boost the entire climb which was several minutes - not something you would be able to replicate typically on the street. I was at 8+ PSI for up to 30 seconds at a time for parts. :yumyum:

This would, I think, qualify as EXTREME punishment. I wouldn't even do that to a car on the dyno.

Interesting observations/measurements -
Ambient temperature was 88°F at the foot of the climb and 72°F at the summit.
My coolant temps started at 202°F and finished at only 218°F.
My air intake temp was 100° at the base and 82° at the summit.
My A/F stayed at 11:1 for almost the entire run.

Net effect of all of this?

My idle vacuum is now about -58 kPa.

Conclusion? Punishing your motor is good for it.

Please feel to discuss.:rock:

Did your internals grow from heat and the clearances became tighter?

hey, there are children on this board.

Heh. My internals usually grow prior to heating. Hard to develop any real friction otherwise.

The effect has remained now after the motor has cooled completely, so I wouldn't think it is a short-term thermal result. There is simply something changed about the motor after "abusing" it that is positive in result.
It is worthwhile to mention that the idle is also smoother and the throttle response feels equally improved. Power is hard to judge since it is usually outrageous, anyway.

Fuel economy was good on the trip, but it often is when I just have highway miles. I normally see exactly 200 miles on a tank of "normal" driving and I saw over 300 on all four tanks on this purely "highway" trip.
Perhaps some sort of carbon deposit is now gone? Smoothing of the rotor chambers? Leveling of the seals? Improvement of the MOP? I don't know...

The only way to get conclusive proof is to help turbo my car and run the test again.

I've noticed that even quick runs to 9k will improve throttle response and power temporarily. I just speculated that it was the ECU adapting the fuel trim to the driving style. After a while, the engine "high" becomes normal again. Need.. another... hit...

The only way to get conclusive proof is to help turbo my car and run the test again.OK. Go ahead. I'll sit here at my PC and await your results.:wiggle:

You must have missed the HELP part ;) I'm only good at thrashing my car around the interstate like a madman with his ass on fire.

Anyway, I don't know if your conclusion is correct, but I want to beeeeeeelive.

I've noticed that even quick runs to 9k will improve throttle response and power temporarily. Yes, this has been noted elsewhere.
But that is not the point of this thread.

The above noted activities yielded a measured increase in idle vacuum. This is an empirical improvement in effective compression ratio.
Were not really talking about a direct performance change, just a difference in engine data.

I can concur on a similar observation. Whenever I do a track day and drive the car (#) at 9.5/10...it always runs much better when I go back to normal driving (#) on the way home.

I have noticed the exaust tips are burnt of completely white as well...and the plugs are a purfect light tan color. After about 2 weeks of around town driving the car starts to idle poorly and stutter on pickup (#).

I'm going to check the Vac tomorrow..and then again after Wed and Thurs track days and see if there is an improvement

this is a bit simplistic,

but thicker oil... better seal. better seal less blow by.... less blow by less heat.... less heat.... less ecu drops timing.. less ecu drops timing better gas mileage...

i have been doing premix for the last 4 tanks... reason, pm....

what have i noticed.... more power. mpg up 2mpg...

Same oil for me.....no heating problems

I know the ECU isn't pulling timing from the logs

So there must be something to it :D:

I do use premix at the track though.....HUMMMMMM :)

my idle must be most excellent then ... :)

30 seconds of 8+ PSI separated by 30 seconds of ~5 PSI over 5 or 6 minutes.
That is 6 minutes or so of nearly continuous boost.

Looking a the map, it may have been almost 10 miles of continuous climb on rt.5 along Lake Castaic.

I'll be interested to hear the vacuum readings after you change your oil the next time :fingersx:

I don't think it will change much - I'm not going to anything heavier.

It is also interesting to note that I consumed no oil on the trip. The dipstick is reading exactly the same as he did when I left Phoenix on Saturday morning, though he's tired.
The oil level is the same as well.

I'm out of 5W-20 royal purple, I was planning on trying 5W-30, which I will do now just for fun and see what I think.

5w-30 should produce the same result since the hot viscosity is the same.

Good point, I missed that you were using 10W-30

I can concur on a similar observation. Whenever I do a track day and drive the car (#) at 9.5/10...it always runs much better when I go back to normal driving (#) on the way home.

I have noticed the exaust tips are burnt of completely white as well...and the plugs are a purfect light tan color. After about 2 weeks of around town driving the car starts to idle poorly and stutter on pickup (#).

I'm going to check the Vac tomorrow..and then again after Wed and Thurs track days and see if there is an improvement

I was at the Maz Fest and looked for Mazda Manic in the infield. Remember that dust cloud?

Anyhow, same results here better idle and running, then after a couple of weeks
same trashy pig rich conditions. :beer05:

5w-30 should produce the same result since the hot viscosity is the same.


i thought that the lower # was the cold viscosity and the higher # was the warm????

beers :beer:

i thought that the lower # was the cold viscosity and the higher # was the warm????

beers :beer:Correct. I'm using 10w-30. He wants to use 5w-30. The warm viscosity is what we are talking about and those are the same.

Correct. I'm using 10w-30. He wants to use 5w-30. The warm viscosity is what we are talking about and those are the same.


i was looking at the change fred was going to do from 5 20 to 5 30 which is what i did....

thanks mm

beers :beer:

I might even try 0w-40 Mobil 1 and see what happens.
This is the oil Porsche recommends.

I might even try 0w-40 Mobil 1 and see what happens.
This is the oil Porsche recommends.

mm,
i am very suprised that you run mobil 1 ... do you get some sort of deal on it?

beers :beer:

No, why? It isn't particularly expensive and it is virtually chemically-inditinguishable from significantly more expensive synthetics.

It is certainly better than any conventional oil and I've been using it almost exclusively in my cars since 1993.

No, why? It isn't particularly expensive and it is virtually chemically-inditinguishable from significantly more expensive synthetics.

It is certainly better than any conventional oil and I've been using it almost exclusively in my cars since 1993.

why,
the comments made by the higher ups at mazda in the seven stock thread.... i can find it if you like... pm me if you want it...

i am not bashing... just making an observation.

plus rp in the five gallon jug is a deal...

beers :beer:

why,
the comments made by the higher ups at mazda in the seven stock thread.... i can find it if you like... pm me if you want it.OK. I'll bite. Put the link here since this is an oil discussion of sorts.

I'm sure the RP is great stuff. So is Amsoil.

However, it is hard to beat $20 for a 5 qt. jug of Mobil 1.

You do realize that all synth motor oils are essentially the same oil stock and that, even at minimums, the cheapest pure synth oil still surpasses the performance of dino oil?

I don't really care about the detergents and other junk. I change my oil too frequently for it to matter.

EDIT:

I found the old post by RG about the conversation he had (in Engrish) about the use of synth oil in a rotary.
Multiple endorsements for synth in general. One obtuse reference to Mobil 1 being the "worst" choice of the available oils. I'll take that with a grain of salt.

that climb is really fun. i left Nemesis *and a bunch a 7s so far behind me doing that hill that i waited for over 5 minutes at thr top befor eany of them caught up. i wasnt checking vacuum or anything else at the time but my oil usage on that trip was significantly lower than what i thought it would be - i only added maybe half a court once the whole trip to 7stock and back.

its not the hill obviously just that i really drove my car hard several times on tha trip and it definetly drove and idled better afterwards for awhile. definelty burning carbon off and leaving less behind i think. better compression and ignition (because the plugs are nice and clean)

OK. I'll bite. Put the link here since this is an oil discussion of sorts.

I'm sure the RP is great stuff. So is Amsoil.

However, it is hard to beat $20 for a 5 qt. jug of Mobil 1.

You do realize that all synth motor oils are essentially the same oil stock and that, even at minimums, the cheapest pure synth oil still surpasses the performance of dino oil?

I don't really care about the detergents and other junk. I change my oil too frequently for it to matter.

yep,

and kinda...

give me a few, this might take awhile...

beers :beer:

The RP is $114 per 5 gal pail right now thats about $28.50 per 5 qts...so it hasn't gone up that much...only about $5 since last time I bought it. This is for the standard 5-20, 5-30, 10-40, grades. The racing oils are more expensive....

The RP is $114 per 5 gal pail right now thats about $28.50 per 5 qts...so it hasn't gone up that much...only about $5 since last time I bought it. This is for the standard 5-20, 5-30, 10-40, grades. The racing oils are more expensive....

wow,
last time i got it it was 102 shipped...

beers :beer:

OK. I'll bite. Put the link here since this is an oil discussion of sorts.

I'm sure the RP is great stuff. So is Amsoil.

However, it is hard to beat $20 for a 5 qt. jug of Mobil 1.

You do realize that all synth motor oils are essentially the same oil stock and that, even at minimums, the cheapest pure synth oil still surpasses the performance of dino oil?

I don't really care about the detergents and other junk. I change my oil too frequently for it to matter.

EDIT:

I found the old post by RG about the conversation he had (in Engrish) about the use of synth oil in a rotary.
Multiple endorsements for synth in general. One obtuse reference to Mobil 1 being the "worst" choice of the available oils. I'll take that with a grain of salt.

damn you, and i searched for at least 3 min to find that..... my guess is it is the old seal thing.... but here is the link.

http://www.rx8club.com/showpost.php?p=1081332&postcount=74

once again i am not bashing...

beers :beer:

Yeah, that's the one. Just too much second-hand info with no science. I don't care how big the name, no science equals no cred.

I noticed very similar results but I have not changed to any higher viscosity. Anyway, it was a mostly highway trip for about 200 miles and it involved...lets say sum very fun driving ;). Anyway, in town I get about 170-200 mpg. After this trip which involved several runs to 9k, I noticed I had gone over 200 miles and still had more than a qtr tank left! It really made me wonder, but I was happy. I want to tun a thicker viscosity oil, especially since its summer time now and its getting hotter. My idle is not very good, but it is a little lean for my tastes. I heard that rotaries should idle at 11.5 or so. My idle is between 15 and on occasion spikes to over 16. I am wondering how to reduce the fuel at idle. Any experienced emange people reading?? I would like to use heavier oil and add sum fuel at idle, and I think it would help sum.

i tried 20w50 here in South Africa, and my MPG went from 15 to 22, my 8 is doing 33000kms and i'm using 95 octane unleaded

Wow, thats huge! Any other success stories??