There is an oil pressure relief valve that is built into the oil system. I wanted to ensure that people knew I have made no modifications to any of the pressure relief systems.

The oil filter has a bypass valve that is around 72psi which is just designed to keep the filter from blowing off the motor.

The oil pump is driven by RPM so I don't see any reason why the pressure would increase with load on the motor. I was rev'ing at a full stop so if there is any increase in pressure it would only further prove my case.

There's plenty of pressure available with a 20 weight oil. If the oil couldn't maintain factory pressure levels then Mazda wouldn't have recommended it. It's that simple.

The notion that synthetics cause leaks in high mileage motors is mostly a myth with very little fact to back it up. My previous vehicle was a 1991 Lincoln and I got it when it had 90,000 miles. I switched over to Mobile 1 full synthetic and never experienced any leaks what so ever.

If you have deposits that are plugging holes in gaskets or seals then removing those deposits could cause oil leaks. However, it's not a fault of the oil but rather the fact that those seals or gaskets need to be replaced.

 

Weird then how some supposedly don't have enough pressure with 5W20 after 1000 miles on the oil. I am going on a long trip out of town this weekend and so hopefully if everything gets installed right I will post up real world data in 100+ degree weather.

 

AFAIK, the old-car leak issue was an early problem with synthetic oils that did not cause the seals to swell, like mineral oils do. So "swollen" seals in older cars would subsequently shrink with synthetic oil. Which was a bad thing because they had worn-in and mated with rotating parts under the swollen state.

That was resolved in the '70's, I believe, when they began adding seal conditioners to fix that behavior.

As for the other, I have a hard time imagining sludge as an effective sealant, but I could be wrong!

 

Yes! That's correct I forgot about the issue with seals not swelling causing leaks. I agree that sludge or other deposits wouldn't make much of a sealer in any situation but that's been all part of the myth that synthetics cause leaks.

Some of that might come down to the quality of oil you are using or what type in particular. If you have a 20w oil that thins out to a large degree then I could see there being an issue with pressure loss. Mineral oil will actually thicken as time goes on and the VII's wear off.

However it comes back to the notion that Mazda wouldn't suggest an oil that cannot maintain factory pressure requirements. While I'm not going to say Mazda does everything that is the best interest of the engine's overall life that is a major detail that just wouldn't be overlooked.

If OD has other data to suggest a particular 5w-20 doesn't hold proper pressure even at normal temperatures I'd be interested to see it.

 

 

SOOOOOOOOOOOOO (Therefore),

Since oils lose viscosity over time with usage in internal combustion engines, do we want to start off with a 20? Then Mazda even recommends some rather long oil change intervals even with the oil remaining in the lines and cooler/s.

One more time: The manufacturer needs to do what they need to do to bring vehicles to market (Cost-wise and in terms of governmental standards). We, the sharp, discerning enthusiast buyers need to do what we need to do to take care of and enjoy the products to OUR satisfaction. Do not believe for a moment that everything they suggest is for the enhancement of the engine's longevity.

A 40 is what most people should be using, and a 10W40 is perfect in the USA all year round.

Paul.

 

Well it kind of depends on your change intervals for the most part. Typically a strict 3,000 mile CI would mean you could use a mineral oil without having to worry about any of the VII's totally breaking down. Otherwise use a synthetic which isn't prone to major viscosity swings and you can go longer intervals between changes.

My point with the 20w was that if it honestly didn't produce enough oil pressure to meet the min. factory standards then Mazda would have been seriously retarded to even suggest it. You might as well sell the car without any tires as I would have put it on that level of stupidity.

From a pressure standpoint the 5w-20 RP that's in my own RX8 with 85,000 miles (1,500 on this change) produces much more than the factory required pressures. That's the only point I was trying to make.

Oils are going to have vastly different behaviors when it comes to viscosity changes. I saw a couple UOA's from Mobile 1's 0w-40 and some people found that the oil had thinned to within the 30w viscosity range at operational temperature. On the other hand you have the favored 0w-30 German Castrol that tends to be on the edge between a 30w and a 40w and wasn't prone to the same thinning.

Those are elements Mazda cannot control and would be dependant on the owner picking what fits their useage the best. That's the area that you either make your own decision or go with the oil the dealership provides.

 

Mazmart is spot on in their statements, all of them.

Your 20W oil becomes a 10W in about 1200 miles. Then 1800 miles later you change 4 of the 7 quarts of the oil the motor.

The bearing damage speaks for itself, and is a result of insufficent hydrodynamic film strength of a light weight oil.

 

All 5W20s are not the same. Which is one of the good points this Dr Haas made. If you send 2 virgin oils for analysis you'll see that they can fall on the far sides of a range for their designation cst at 212F or whatever. I would feel much safer with RP 5W20 than some cheasy dino 5W20 but I'm still not running a 20. Do as you see best dear friend. The entire world is pushing for thinner oils in terms of government mandates. I'm not making this up for the fun of being a conspiracy theorist. I know this from reading technical papers. Energy conservation rules supreme. This translates to: Find a way to use thinner oils. The rotary has some particular needs that are sometimes forgotten, EVEN BY MAZDA ENGINEERS! How do you think we ended up with the fuel flooding problem or improper oil metering? Mazda recommended 5W20 for the DISI turbo engines but after changing God knows how many turbos trying to solve smoking they have realised that a change to 5W40 syn is the cure (Applied only with a complaint ).

Apply a grain of salt to everything you read or encounter in life!

Paul.

 

That's why I'd say follow for sure the suggested 5w-30 or 0w-30 suggestions that Mazda has issued to everyone else as that makes much more sense. Mazda had to make a lot of compromises to get past US government EPA regulations which no doubt played into the OMP injection amounts and emissions control.

At the end of the day as you said Paul it's a balance of what is going to bring the car to market while also ensuring the car lasts throught the warranty period. Everything after that doesn't matter.

 

flash--data --well what do ya mean--i can give testimony--i ran 5/20 when i bought my car in dec 2003 --put mechanical gauges on it shortly afterward--- pressure at 280 F and 3K was approx 48lbs. also saw the same pressures from royal purple 5/20. oil temps where 180-190. every rx8 here in Ga that has gauges and ran that light weight oil saw the same.
If you got 70 then i dont understand--heck at 3K with a 40 wgt i dont get 70. its in the 60's.
what pressures are you getting at 8K or so--whats youre highest reading?
heck you have 09 type pressures?
someone gave you a new 09 motor while you were sleeping man!
od
OD

 

TOUCHE' Paul

While on Oil, my local Mazda Dealer Tech told me the main reason Mazda increased the Sump capacity on the 09 RX-8's (RENESIS II) to the largest volume and area they technically could achieve was not because it gave owners a "longer" breather period before oil top-offs, but to improve the ratio of new clean OIL to Old USED oil left in engines oil network when servicing.

As he said, Ideally if you could drain out ALL the old oil in your oil coolers the better, or if you can (financially) do two oil changes..

Example...
Drain old oil, refill with clean, run engine to full operating temperature, drain oil again, then change filter and re-fill.

 

I guess the question could also be asked...
1. How accurate are your guages?
2. Does Mazda read/measure publicized Oil Pressure stats from the same location that you guys do?

 

i believe measures theirs from the oil pressure sensor site--while i read mine from the oil filter plate-only about 5 inches away?
guages was an auto meter mechanical gauge --which at the time was considered more accurate than electrical---later when i converted to ProSport electrical gauges--- i got the same reading i was getting with the auto meter.
just dont understand it--it wasnt just my car either.
OD

 

You sure you were taking pressure reading at 280 degrees and not 180 degrees? If you were running your oil at 280 degrees I wouldn't care if the oil created a wormhole in space time...that's WAY too hot for the motor to sustain any kind of lubrication.

My pressure gauge is located right under the oil filter so the filter bypass (or internal bypass) only allows up to 72psi of pressure. I've seen pressures hit as high as 80psi at high RPM's but if the pressure exists higher than that elsewhere in the oil system I wouldn't have any means of seeing that.

If you are only seeing 60psi @ 3,000 RPM's with 40 weight oil then I'd suspect either the gauge isn't reading correctly, there's an issue with the location you are taking pressure readings from or something else is going on. That seems rather low for that viscosity of oil.

I can only speak from experience on my own motor and currently of the various RX8's in Phoenix I have access to I'm the only run running dedicated oil temperature and presssure gauges.

 

screw you all !

Im so going to buy 10 quarts of 5w20 this or next week, change my oil TWICE. just to be sure that I have almost none of the 20w50 left. then I'll read the pressure !

I have Defi Gauges probably one of the most accurate on the market !

I will drain it back out after the test tho. I dont want any 5w20 to stay too long inside my engine

hmm, which oil should I use .... Synthetic .... I get Mobil1 then.

 

Don't forget to add Crushed Fridge Magnets to your oil also, so they will pick up any metal particles floating around under 25 microns.

Before you change your oil, Stand on your head in the corner, recite the Felix **** Bible, I shall not use synthetic oil, I shall not use synthetic oil, I shall not use synthetic oil, I shall not use synthetic oil, I shall not use synthetic oil, 10 times.

And I forgot, your RENESIS must be facing the South Pole.

 

Yes sir !

Will do sir !

 

Well as I said, I will have an answer this weekend. My pressure sensor and temp sensor will be right under the oil filter.

I am running German Castrol Syntec 0W30. I didn't do two oil changes but I did get 4.5 quarts out so there is a little Mazda 5W20 in there.

 

Say what? I was told that I had to do this crazy naked dance around the garage and...

Why is everyone looking at me like that?

 

I think that was my point; modern oils have detergents as well and so they should clean just like synthetics. Whether synthetics clean better or not is up for debate, but that's mainly an additive package issue.

 

Brings new meaning to the term rotarded...

 

Or re-Todd-did

 

dont forget you also have to spit over your left shoulder after turning around 3 times!! most important part

No my oil wasnt at 280 degress lol and mine (ours)was from the same area as yours--the oil filter plate (RB's). I checked mine while cruiseing at 3K, not revving while parked--so the engine had a load on it. Shouldnt really make a difference?
Has to be a reason mazda changed the oil pump design for 09 and when to higher pressures.
If you get 70lbs at 3 K at that temp with a 20w what are you getting with a 40W?
interesting stuff.
olddragger

 

you forgot about the base stock.

Thats the biggest reason why Synthetic will lube, handle heat, and last longer than Mineral brotha.