spoke to a 3rd gen rx7 owner this weekend he was running 20-50 and has had no troubles other than the coolant issues those cars have. bought some 20-50 and switched it on sunday..

 

Thanks.

More thoughts

1.If the issue comes from cold start, would not it be better to increase the speed of the cold oil flow, to decrease the time to get the bearing? A cold 0w is much thicker, than a warm xxw-50.

2. Is the rotaries e-shaft hotter than a crankshaft? I think yes, but what about you? Maybe the wear comes from too thin hot oil.

If the 1. and 2. points are true, than we need 0w-40, 0w-50.

Is it true?

 

Why run 20W-50 when you can run 0W-50. I know your in Miami so cold is not much of a concern but I grew up in FL and it does occasionally get cold. I would not want that cold 20W in my car when its 30 degrees out.

 

That's just it; the problem is not from cold start. A XW-30 or 40 would both be better for a rotary than 5W-20.

Paul.

 

ambient temp with humidity is anywhere from 90f- 96 here, so my oil is warm from sitting in the sun all day the temp wont drop for another month and a half when my next oil change comes around. i try and change it before 2k miles (about 2 months). at that time i'll run something a little thinner dont think i'll be doing a 0w tho.

 

a "true/good" Synthetic based oil would flow just fine as cold as 10f degrees.

So 30 degrees is not really "that" cold

Even Dino based 20wXX would flow just fine at around 25f (its gonna get pretty thick, but manageable.)

20w50 oil cost about the same as the 0w50, so ... lemme finish 10 qts of my 15w50 mobil1 and 5 qts RP 20w50 first ...

 

Yeah I just don't see the point when they cost the same.

 

people afraid of wide range oil bcuz of the additives package. they have to add tons of them to get such "wide range" viscosity.

Im ok with it tho. Like I said I will try some when Im done with my 15/20w50 stock

 

Really, you guys are lucky, here a 20W50 is dirt cheap ($22), a 0W50 is about $60 and only Synthetic of corse.....

 

...

yeah Dino 20w50 is dirt cheap here. I can get 5 qts with filter for 17.99

But Synthetic ... well. its not that much. I got Mobil1 5 qts + Mobil1 filter @ autozone couple days ago for 29.99 + tax.

More exotic brands like Redline/Eneos/Royal purple will cost about twice as that without filter.

 

A 0w has the same operational temperature viscosity as a 5w or 10w oil does. The only difference is when the oil is cold. A 0w-50 will technically have a lower cold viscosity than a 20w-50 will. This ensures you have the best protection when starting your vehicle. 0w oils are also true synthetics.

 

To respond to the Eccentric Shaft 'Heat' thought....as we know FD RX-7's were a massive Heat Machine with twin Turbo a 15W40 was the oil recommended (here).

One would "think" the e-shaft on a RENESIS would get no hotter, so was SG bearing wear an issue with FDs...have not heard/seen., but the Oil Pump is different by part number for the Turbo...like the oil pump is different in the FE S2.

 

As for weights, we should be looking beyond the numbers on the bottle, no?

For example, looking at Royal Purple's data, at 40c, 0w40 is heavier that 5w20 and 5w30, but is lighter than 5w40.

At 100c, 0w40 is heavier than both 5w20 & 5w30 (of course), but only slightly thinner than 5w40, which is very thick at 40c.

So, I can see why 0w40 is popular. But, you have to look at more than just the label on the bottle.

[edit] I see other responses above on this - I started this response 20 minutes ago. Sorry for the duplication.

 

I pulled the 5W20 out of my RX-7 and filled with 5W30. It feels the same. Then again it felt the same with 10W30 and 10W40 too.

 

Butt Dyno is not that Accurate. you should know better

 

i understand that point but if its hot all day in the 90's (f) do i really need to go 0w? during the summer it never drops below 85f (at night!) so im under the impression that my oil is always gonna be warm(?) i may be wrong so plz feel free to correct. in about 2 months when it actually is cold ill switch it up but for the rest of the season i think 20-50 is the way to go.

 

.

 

As I said in the other thread, bearing heat generation and wear is related to the square of the surface speed differential across them, so the jump from 7krpm to 9krpm is quite a step in terms of heat/friction in the bearing, that's 65% more heat and wear right there.

 

Yes Phillip, the Higher RPM of the RENESIS has always been in my mind as a possibly issue, because most (all) things being equal, Oil Grade recommendations and Higher RPM's are new...when compared to the RX-7.

Perhaps part of the reason Mazda increased Oil Pressure & By Pass Pressure in Series II RX-8's, oil flowing/circulating faster through Engine and Oil Coolers 'should' remove heat more efficiently.

Series I RX-8's for Australia only had One Oil Cooler, Manual and Auto!..
But, now Series II's here in Manual have two, but Auto's still only have one, they now have the higher power 6 port engine auto????

One would think Australia has a Hotter climate than the UK?
But the UK models always had the 2 Oil Coolers???...

Go Figure??

 

^ Leads one to believe that the folks over at mazda have their thumbs up their as*es..

 

remember all what Paul said---"THIS IS NOT A START/WARM UP PROBLEM"
(sorry for the capitals), so its not about the weight of the oil when it is cold.
Actually in a way it is not about the weight when the oil is hot either---its about film strengh . But, it is a whole lot easier to talk about viscosity than film strengh and they are fairly closely related unless you want to get exotic.

You dont have to worry about the oils temps so much. Just get your coolant temps where you want them and the oil temps will follow.

Paul/?Ash yall rock dudes!
OD

 

yes, it should do, it'll also stop the oil breaking down as fast which some people are experiencing (i.e. 30w oils becoming 20w after 3k miles) - that's normally caused by excessive heat and load shearing the oil molecules.

IMO that's why people are leaning toward thicker oils - when they do break down they're at the right viscosity, but the problem with that is when they've broken down most of the additive packages have been used up - leading to carbon buildup, crankcase sludge and a lesser ability to suspended foreign particles - which also ties in with the scuffing seen on some of the stationary gearsets - those particles are settling and damaging the gearset instead of being help in suspension, and because the MoS2 and other dry lubricants are falling out of suspension too, their film thickness drops as they aren't being replenished - so they can't help either.
It'd also lead to a bit more scuffing wear on startup.

Now, I know our engine is different as it's not for road use, but the way I see it, everything is basically the same, going by the 'thicker oil is needed' theory, we should be destroying engines every ten minutes.

We're constantly above 6krpm, regularly at the limiter, always under heavy loads, and we generate enough heat that we've melted the electronics off the side of the alternator...
And yet, we're getting away with 5w-30 with no trouble, no scuffing and the bearings were good enough to again after a checkover.

So what's different?
Well:

a)Good quality fully synthetic oil - I know it's another debate in itself, but the stability of a good synthetic and resistance to shear is a step above most semi-synth or dino oils.

b)Absolutely massive oil cooler - the oil going into our engine is going in at ~35*c, yet it's still coming out at ~130*c on the sensor in the oil cooler inlet - now, given most dino oil starts to break down rapidly above 120*c, you can see why I suspect the high oil temperatures are part of the problem - imagine what temperatures you're oils are getting to given your coolers have perhaps half the area of ours....


What you've mentioned Ash, with the higher pressure for the new models, just reinforces that to me - seem like they're trying to get the oil in and out of the engine faster to lower the peak temperatures the oil is experiencing.
Incidentally, that extra flow will also boost the loads the bearings can cope with massively

 

Just hope the Rear Main Oil Seal Holds up with the increased pressure, same seal as ALL FD and ALL FE's.
Front Timing Cover Seals is also the same for both series RX-8's.

 

And, just to be clear, you state this because the higher flow rate will remove the heat generated by the bearings (which as you have stated is higher than past rotaries due to the Renesis' higher redline) more quickly, correct?

 

Gas mileage hasn't changed either. That would be indicitive of an efficiency difference in the oil. I ported my throttlebody and got a mpg gain. Oil isn't doing anything.