LiviuRuican

rx-8
Ulei semi-sintetic sau de care?

12 posts in this topic

Salutare!

Sunt posesor de mazda rx-8, imi poate spune si mie cineva de unde pot cumpara uleiul pentru motor (doar dexilia) si la cati km se face schimbul?

 

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P-aci prin zona asta a forumului te-ai uitat? :)

Ca idee, cumpara uleiul care trebuie si doar de la reprezentanta/magazine/distribuitori de incredere, ca sa nu ai neplaceri ulterior

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Este ulei dexelia nu dexilia, este un ulei de calitate produs de grupul Total producatorul uleiurilor OEM si pentru grupul Citroen

Dexelia nu se comerializeaza in RO decat prin reprezentantele Mazda, mai rar vei gasi pe net pe la anumite magazine online dar nu sunt decat pentru diesel si-s stocuri limitate si vascozitati aferente stocului adica nu pot gasi asa usor 0w20 de exemplu care-mi trebuie mie , pentru benzine mai rarut ca-i mai dragut.

Arunca un ochi aici si vezi ce cod motor ar ca sa stii ce vascozitate trebuie http://cararac.com/engine_oil/mazda/rx-8.html

Nu cred ca la RX-8 este necesar doar Dexelia, parerea mea personala este ca poti pune orice ulei de calitate cu vascozitatea recomandata de producator (5w30 din cate imi dau seama,desi in practica s-ar putea sa trebuiasca ceva mai vascos pentru ca ...rotary motor) ,dexelia  din cate stiu este special conceput pentru generatia Skyactiv si  este full sintetic,desi nu-s sigur 99,99%.

Poate te ajuta si https://www.emag.ro/search/Dexelia

 

Daca ai timp sa citesti si cunosti bine engleza , ce recomanda pentru RX-8 baietii astia :

 

For a more detailed explanation of why we recommend 10w40 grade oil for your RX-8 and to find out how using alternative grades can adversely affect your engine, read on… Since way back in 1967, in the days of the Mazda Cosmo 110s, rotary engines have been ran on either 15w40 or 10w40 mineral oil. It was later found however, that switching to using synthetic oils posed a number of problems;

  1. Corrosion of the rubber o-rings inside the engine
  2. The release and then subsequent build-up of harmful deposits inside the engine
  3. Higher cost of synthetic oils which despite being more durable are wasted when used in a rotary engine (See ‘Performance’ below).It wasn’t until 2003 with the dawn of the RX-8 that Mazda started to recommend 5w30 oil, specifically for its flagship rotary-powered sports coupe (amidst claims of better fuel economy and improved performance). The problem with this recommendation though, becomes our fourth problem:
  4. 5w30 grade oil is simply too thin to maintain the oil pressure required to sufficiently protect the Stationary Gear Bearings in the RX-8 engine.

So we now have four major problems, all relating to the type of oil you use in your RX-8. Each of these problems, along with the effects these oils have on the internal components of your engine, are explained further below;

Corrosion of the Rubber O-rings

Synthetics and internal engine components

The rubber oil control ring o-ring’s in Mazda’s RX-8 were switched from the traditional rubber base material to a more modern Viton based rubber material which can better withstand the aggressive chemicals in modern oils. It’s quite normal to fit RX-8 (Viton) rubber control ring o-rings in earlier model rotaries, when rebuilding RX-7 engines (and earlier) for instance.

Release and then subsequent Build-up of Harmful Deposits

Achieving a smooth, clean burn

Fully synthetic oils, generally speaking, are better in every way for automotive use and are used in most cars traditionally. Among the many benefits is an improved durability, better performance and this sort of oil doesn’t break down over time, unlike semi-synthetics. But…

There is an issue in the ability of oil to burn inside your (non-traditional) rotary engine, in terms of how cleanly it burns and this is very important. For whilst some oils may burn cleanly, not all synthetic oils do. Most leave behind dirty substances such as carbon and ash. Deposit build-up of these substances can cause your rotor apex seals to stick and spark plugs to foul. Should carbon build up excessively (causing your seals to stick) the most likely outcome, in terms of a remedy, would be a complete stripping down of your engine for a thorough cleaning of all internal components and then rebuild. This is about as serious and major as it gets in terms of repair work.

After almost 50 years of rotary engine manufacture, there are no known cases of anyone reporting issues with excess, un-burnt carbon deposits from mineral or semi synthetic based oils when used in engines, that are otherwise well looked after and used properly. So it is well proven that mineral based oils work and work well in rotary engines, where fully synthetic oils often do not.

Higher Cost of Synthetic Oils

Keep it mineral-based, semi-symthetic and change it regularly!

The down side to using mineral based engine oils is that they don’t last as long as a synthetic oil. In time, all lubricants lose their ability to lubricate as molecules are dispersed by evaporation and oxidation. Additives are added, designed to combat and control acids and viscosity, these additives are normally consumed as they do their job too. Synthetic oils are proven to withstand this degradation up to as much as 5x times longer than comparable mineral based oils. However, because the oil in the sump of a rotary engine needs to be kept clean in order for it to be injected into the combustion chamber, regular top-ups and complete oil changes are very important – regardless of whether synthetic or non synthetic oil is being used.

In short, this means that the highly recommend 3-6,000 mile oil changes negates any benefit of having a longer lasting synthetic based oil in the sump. Fortunately though, mineral based oils are generally significantly more cost effective than fully synthetic varieties, making the cost of those regular oil changes that little bit easier to bear.

5w30 = Too Thin to Maintain Oil Pressure

Viscosity

As mentioned above, rotary engines traditionally have always been run on a 10w40 or 15w40 grade mineral oil, especially in the UK.

As we understand it, the RX-8 engine code, 13b MSP, was designed no differently than the RX-7 engine codes before it (13b REW’s, RE’s, DEI’s) and so we assume that Mazda technicians had every intention of using the same grade of oil in the MSP as they had used previously in the RX-7. So why the change in recommended grade of oil to use?

Well, in 2002 ‘Total’ sold Mazda the concept of achieving better fuel economy by using a thinner grade engine oil. Mazda responded by introducing 5w30 across their entire range of cars, and a lot of other car manufactures at the time quickly followed suit. It is true that using a thinner grade oil will cause less drag in the engine and in turn, unlock a little extra horsepower and slightly improve fuel economy – at an almost un-measurable rate in terms of the day-to-day running of a rotary engine it must be said!) It is also true that many modern day, highly tuned, piston engines must be run on thinner and thinner engine oils as well.

It wasn’t until the RX-8 owners had started to break through the 50,000 mile benchmark that rotary specialists (such as ourselves), started to notice the problems that the thinner grade oils and low oil pressures were causing in the Renisis engines.

Stationary Gear Bearing Failure was fast becoming a phrase synonymous with RX-8 engine failure among enthusiasts and specialists alike. We see it all too often at Rotary Revs and in fact, every single RX-8 engine that we have ever stripped down (regardless of mileage) has shown some level of wear on the stationary gear hydrostatic bearings.

This is why we insist on switching to 10w40 engine oil, to help counteract this issue and hopefully extend the life of your engine and protect those gear bearings.

To summarise:

Your RX-8 Renesis engine needs oil to lubricate it’s bearings. This is important in order to avoid the harmful build-up of ash and carbon which can cause rotor apex seals and side seals to stick.

The thinner grade oil recommended by Mazda (5w30) is too thin for the oil pump inside the RX-8 to maintain the oil pressure necessary in an idle state, at low revs per minute (RPM). So, for this reason we enforce a strict 10w40 oil policy on all cars we work on, to help reduce the wear of the Stationary Gear Bearings, thus extending the life of your engine.

Rotary Revs thoroughly recommends draining, completely, and changing your oil at least, once every 12,000 miles or per annum; ideally changing at every 3,000 – 6,000 miles, topping up whenever necessary. See our Service Schedule for more information and other servicing options.

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On 4/28/2018 at 8:07 PM, jakavelli said:

parerea mea personala este ca poti pune orice ulei de calitate cu vascozitatea recomandata de producator

..E si parerea multora, majoritatea hulind mazda ulterior pentru probleme de fiabilitate a motorului. Viscozitatea si norma nu e totul in cazul rotativului, mai sint lucruri mai complicate de atit.

On 4/28/2018 at 3:49 PM, LiviuRuican said:

Sunt posesor de mazda rx-8, imi poate spune si mie cineva de unde pot cumpara uleiul pentru motor (doar dexilia) si la cati km se face schimbul?

 

De la orice dealer mazda. Cere uleiul 5w30 pentru benzinare, nu ala pentru dieseluri.

Vezi ca s-a mai discutat problema pe aici, e posibil sa iesi mai bine cu un mineral 10w40. Urmareste de aici post-urile userului @Dazzed:

 

 

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Va salut!

Din nou revin cu o intrebare in legatura cu uleiul la rx-8 (mai degraba o nelamurire)

Cu totii stim ca in motoarele rotative se baga ulei semisintetic sau mineral, in schimb mazda ne recomanda uleiul ei dexelia, care este un ulei 100% sintetic.

De ce si cum?

Adica nu se baga uleiuri sintetice pentru ca, crapa motorul, dar se baga dexelia.

Sunt bagat in ceata complet, rog un specialist sa ma lamureasca si pe mine!

Multumesc!

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1 hour ago, LiviuRuican said:

Sincer nu stiu ce sa cred!

Poti crede ce scrie pe site la Shell, nu pe site la emag. Pe site la shell spune clar ca e ulei sintetic. Eu asta as crede.

Am dat mai sus un link in care @Dazzed recomanda Total Quartz 5000 15w40 sau 10w40. Ambele sint minerale. Scrie pe site la Total. Si asta poti sa crezi.

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6 hours ago, LiviuRuican said:

Cu totii stim ca in motoarele rotative se baga ulei semisintetic sau mineral, in schimb mazda ne recomanda uleiul ei dexelia, care este un ulei 100% sintetic.

De ce si cum?

 

Mazda stie ca se va pune dexelia in rotative asa ca el este special aditivat si formulat pentru a arde curat. Arderea curata nu e o cerinta pentru uleiurile sintetice, este doar o posibila proprietate care totusi poate fi imprimata unui astfel de produs daca este necesar, chiar daca ea caracterizeaza mai mult uleiurile semisintetice si minerale.

 

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Am inteles.

Practic datorita faptului ca dexelia are arderea curata e singurul sintetic care sa baga in rotative. Si cum ramane cu vascozitatea? 5w30 am inteles ca ar fi cam subtire. Ar fi indicat sa o trec pe un mineral 10w40? 

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Am pus cu citat de pe un site al unor domni din Anglia care serviceaza de ani de zile mazda rx-8 , oamenii stiu ce vorbesc si au spus ca desi producatorul recomanda ulei sintetic 5w30 ei personal recomanda un ulei mineral 10w40.

Este asemanator cu lucrul pe care-l fac soferii la masinile diesel sau cele foarte forjate (multi km) o masina de nou care mergea cu ulei 5w30 dupa 300.000 km il va hali repede, soferul a inteles chestia si merge pe un 10w40 care supriza nu se mai "consuma" asa repede.

Motorul rotativ e alta treaba dar 10w40 mineral asa cum spuneau si ceilalti useri nu poate face nimic rau.

Sustin in continuare ca dexelia este altceva , este pentru motoare performante si compresie ridicata exact pe gustul Mazda, japonezii nu au cum sa recomande altceva decat uleiul lor si fiindca in gama lor de uleiuri nu exista mineral asta e!

@LiviuRuican incearca ce ti-au recomandat si ceilalti adica mineral , verifica joja la cat e indicat la rotative a se face servisarea (4000? wtf evident ca indicat este sa-l verifici saptamanal) si compara cu ce nivel aveai inainte, vei sti daca acest ulei este pentru masina ta sau nu. In schimb vezi sa iei ceva de calitate, acuma eu stiu ca la uleiuri minerale Aral sunt cei mai vechiuti dar nu cred ca este de calitate cel putin nu la noi in tara. Conteaza foarte mult ce marca este uleiul ca si la anvelopele auto de acolo si diferentele exagerate intre anvelope de aceleasi dimensiuni precum si uleiuri de aceeasi vascozitate, pretul arata calitatea intrun final.

"5w30 = Too Thin to Maintain Oil Pressure

Viscosity

As mentioned above, rotary engines traditionally have always been run on a 10w40 or 15w40 grade mineral oil, especially in the UK.

As we understand it, the RX-8 engine code, 13b MSP, was designed no differently than the RX-7 engine codes before it (13b REW’s, RE’s, DEI’s) and so we assume that Mazda technicians had every intention of using the same grade of oil in the MSP as they had used previously in the RX-7. So why the change in recommended grade of oil to use?"

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Daca citeati cu atentie vedeati ca oameni aia din UK ziceau ca pompa de ulei nu poate sa faca presiunea necesara la turatii mici cu 5w30 si recomanda 10w30. Oare Mazda nu recomanda ca turatia motorului dupa ce atinge temperatura optima sa nu scada sub 4000 rpm? Deci cei care utilizati Rx8 asa cum trebuie folositi cu incredere 5w30. Cei carora nu va place turatia, aveti alte tipuri de auto la dispozitie. Alta problema este ca pompa si injectoarele de ulei de pe Rx8 sunt concepute pt. 5w30 iar daca se va folosi ulei mai vascos pompa o sa mearga mai fortat iar injectoarele nu or sa poate pulveriza cantitatea de ulei necesara ungerii camerei de ardere.

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