consum ulei?

[XploD]

Stiu..da tre sa il dau jos...nu l-am dat nici o data :lol:

[pmi]

Articolul este putin stufos dar cred ca foarte util pentru a intelege vascozitatea la pornire, la temperatura de lucru, functie si de temperatura mediului ambiant. Sper sa fie de folos celor interesati. Numai bine.

Motor Oils - Fuel Economy vs. Wear

By Blaine Ballentine, Central Petroleum Company

Conventional wisdom states that engine oils that increase fuel economy allow less friction and prolong engine life. The purpose of this article is to challenge conventional wisdom, particularly concerning modern (GF-3 ILSAC/API Starburst) engine oils.

Fuel Economy: Does Anyone Really Care?

First, we should face the fact that the American consumer does not appear to care too much about fuel economy. The No. 1 selling passenger vehicle is the Ford F-Series Pickup. Five of the top 10 best-selling vehicles are trucks, and trucks outsell cars. Some of the trucks are called sport-utility vehicles, otherwise known as SUVs, because their owners don’t want to admit they are trucks. The mass (size, weight) of these vehicles is not conducive to great fuel economy.

Figure 1. Bearing Wear

Additionally, consider how most vehicles are driven. Anyone accelerating slowly or driving at the speed limit to conserve energy is a danger to himself and other drivers who are in a much bigger hurry.

Auto manufacturers, on the other hand, are concerned about fuel economy. The manufacturer faces big fines if the fleet of cars it produces falls short of the Corporate Average Fuel Economy (CAFE) requirements imposed upon them by the federal government.

The March to Thinner Oils

Thinner oils are being used these days for three reasons: They save fuel in test engines, the viscosity rules have changed, and manufacturers are recommending thinner grades.

The Sequence VI-B is the test used to evaluate fuel economy for the GF-3 specification. The VI-B test engine is fitted with a roller cam where the old Sequence VI test used a slider cam. The old Sequence VI test responded well to friction modifiers, but the Sequence VI-B responds to thinner oils.

The test oil’s fuel efficiency is compared to the fuel efficiency of a reference oil in the Sequence VI-B test. To pass, the test oil must improve fuel economy one to two percent, depending on viscosity grade. SAE 5W-20 must produce higher relative fuel efficiency than SAE 5W-30.

It is interesting to note that the reference oil is fully PAO synthetic SAE 5W-30. To qualify for the GF-3 Starburst, ordinary mineral oils had to beat the fuel economy of the full synthetic reference oil. (It seems there is more to fuel economy than a magic base oil.)

Another factor in fuel economy is temporary polymer shear. These polymers are additives known as viscosity index improvers (or modifiers). Polymers are plastics dissolved in oil to provide multiviscosity characteristics. Just as some plastics are tougher, more brittle or more heat-resistant than others, different polymers have different characteristics.

Polymers are huge molecules with many branches. As they are heated, they uncoil and spread out. The branches entangle with those of other polymer molecules and trap and control many tiny oil molecules. Therefore, a relatively small amount of polymer can have a huge effect on oil viscosity.

As oil is forced between a bearing and journal, many polymers have a tendency to align with each other, somewhat like nesting spoons. When this happens, viscosity drops. Then when the oil progresses through the bearing, the polymer molecules entangle again and viscosity returns to normal. This phenomenon is referred to as temporary shear.

Because the Sequence VI-B test responds to reductions in viscosity, oil formulators rely on polymer shear to pass the test. A shear stable polymer makes passing the GF-3 fuel economy test much more challenging.

New rules defining the cold-flow requirements of SAE viscosity grades (SAE J300) became effective in June 2001. The auto manufacturers were afraid that modern injection systems might allow the engine to start at temperatures lower than the oil could flow into the oil pump. Consequently, the new rules had a thinning effect on oil.

The auto manufacturers now recommend thinner oils for their vehicles than in the past. Years ago, SAE 10W-40 was the most commonly recommended viscosity grade, later migrating to SAE 10W-30. SAE 5W-30 is most popular now, but Ford and Honda recommend SAE 5W-20. It is likely that more widespread adoption of SAE 5W-20 and other thin oils may occur to help comply with CAFE requirements.

Because of the change in cold-flow requirements and the fuel economy test pushing formulators toward the bottom of the viscosity grade, today’s SAE 10W-30 oils are more like yesterday’s (GF-1 spec) SAE 5W-30 oils. On top of that, there is a trend toward auto manufacturers recommending thinner grades. This seems ridiculous. SUVs and trucks, with their inherently less-efficient four-wheel drive and brick-wall aerodynamics, need powerful, gas-guzzling engines to move their mass around in a hurry. In response, auto manufacturers recommend using thin oils to save fuel. Incredible!

Viscosity and Wear

Thinner oils have less drag, and therefore less friction and wear. Right? Perhaps in the test engine or engines that experience normal operation. But somewhat thicker oils may offer more protection for more severe operations such as driving through mountains, pulling a boat, dusty conditions, short trips, high rpm, overloading, overheating and overcooling.

Any abrasive particles equal to or larger than the oil film thickness will cause wear. Filters are necessary to keep contaminants small. The other side of the equation is oil film thickness. Thicker oil films can accommodate larger contaminants.

Temperature has a big effect on viscosity and film thickness. As a point of reference, one SAE grade increase in viscosity is necessary to overcome the influence of a 20

[lucastn]

Salut. Motorul meu e 2.0i cod 2e, masina Passat model '94 (intermediar) si papa cam 1 litru ulei la 1.000 km. Am luat semeringurile de supape si tre' sa le montez. Beleaua e ca mecanicii mi-au spus ca trebuie data jos si chiulasa asa ca tre' sa mai dau bani si pe o garnitura de chiulasa, dupa ce m-a secat cea de la capacul axului cu came care mi-a rapit 50 ronisori. Chiar nu se pot schimba semeringurile supapelor fara sa dai jos chiulasa? :blink:

[zonkkk]

Pai nu prea ai cum sa lucrezi la supape daca nu dai jos chiulasa.

Intrebare: De unde ti-ai dat seama ca trebuie schimbate semeringurile de la supape?

[lucastn]

Pai asa mi-au zis mecanicii (am cerut vo' 3 pareri de la diferiti mecanici de prin service-uri). Ei au zis ca prima data la semeringuri e beleaua abia apoi te gandesti la segmenti, set motor, etc. Acu' stiu si eu ? Imi place mecanica da' nu-s asa bazat ca cineva care lucreaza in domeniu toata ziua. ;)

Inca ceva: la un service mi-a cerut 300 ron pentru aceasta operatiune ;) . Oameni buni, trebuie vo' scula speciala (presa, ceva?) la supape ca ma apuc de schimbat in parcare. Mi s-a facut rau cand am auzit cat cerea respectivu. O fac io in parcare, sa moara service-ul de ciuda ;) . Cand am vazut cum lucra astia la masini la fel ca meseriasu' de pe sant si se dau de ceasu' mortii ca-s service-uri cu staif, acreditari ISO si alte cele, imi bag picioarele in meseria lor ;) . Cum spunea cineva de pe aici: vrei masina facuta cum trebuie? Fa-ti-o tu singur ca asa poti fi sigur ca e ok. Si asta am sa si fac. Astept indicatii (si scheme, imagini, daca se poate) despre cum se face lucrarea asta. Precizez ca am manualul de reparatii al lui HRE ;) , asa ca, cu manualul pe genunchi si cu indicatiile voastre o sa-mi schimb semeringurile. Am observat ca in service au program cu reparatii la vehicule dar nu il consulta decat dupa ce-si prind si ei urechile zdravan de tot. In rest, prin analogie cu ce au mai facut pana acum si dupa ureche. Profesionisti, nu? Si te mai trezesti cu ceva bulit pe la masina... ;)

[sebica79]

Pentru aceasta operatiune, schimbarea semeringurilor, o poate face linistit un mecanic cat de cat priceput, in prezenta ta. Nu este asa mult de lucru dar iti trebuie ceva scule.

Semeringurile de supape se duc in general din cauza nivelului de ulei peste cel admis de producator. Se creeaza o presiune mai mare de ulei ce solicita peste masura semeringurile de supape. Doi la mana ar fi pierderea elasticitatii a O-Ringurilor (partea de guma din ele), datorita schimbarilor "bruste" de temperatura repetate. Poriniri si opriri dese in timpul zilei.

[lucastn]

Scule speciale sau chei normale? Am acasa doua truse de tubulare, un set de inelare, o gramada de chei fixe, et. Am cu ce demonta chiulasa, cureaua dintata, etc. ma intreb daca trebuie ceva special pentru demontarea tachetilor hidraulici si a scaunelor de supapa. Acolo ma ingrijoreaza. In rest, dau jos si pun la loc chiulasa fara nici o jena. In manual am vazut ca trebuie o cheie mai speciala la intinzatorul curelei dintate si un tub de plastic pentru montarea semeringurilor in chiulasa. Faza e ca din ce am vazut eu la fata locului, nu ar fi neaparat necesara cheia respectiva. Si parca era ceva (nu mai retin) si despre o presa pentru arcurile de la supape...?

Uffff...grea botanica asta.... :wub:

[Azazell]

Spre exemplu;

glf 4 2001 73800 km reali acum 5 luni iar in prezent 94000km ulei schimbat la 90000km, si nu a papat un gram

sunt sigur ca la consumul tau de ulei anul si kilometrajul masinii tale bijuteria ta a fost vreun Taxi

fara suparare....vinde-o,nu te mai chinuii cu segmentarea :)

[zonkkk]

Nu conteaza atat de mult cum cati km are masina, ci modul in care a fost condusa (sportiv/normal, drumuri scurte/lungi, etc.), ce ulei a bagat proprietarul in ea, cat de des l-a schimbat, si bineinteles exista si o doza de noroc, atunci cand iei masina din fabrica.

Tot spre exemplu, eu stiu un Passat din 1998 1.9TDI, 110CP, cu 300.000km care nu papa gram de ulei si nu scoate pic de fum negru, chiar si cand ii dai in gura. (masina din Olanda, care apropo sa vandut cu 5000EURO in Ucraina, si care probabil ca va avea kilometrajul dat inapoi cu cel putin 150.000km, de samsarii de acolo)

La fel un Volvo din 1995, motor pe benzina, 370.000km nu papa ulei aproape deloc. (500g la 15.000km).

[codrut]

Salut!

Azi m-am inscris si nu ma stiut unde sa postez.

Am si eu o problema cu mas. din semnatura.

De la un timp scoate un fum albastrui pe teava. Cateodata, dupa ce ma dau la ea, zici ca merg cu tractorul.

Ateori merge bine, scoate doar putin, in limite normale sa zicem.

Ar putea fi doar de la semeringurile de la supape, sau eventual vreo supapa stricata, sau este mai grav, gen segmenti si altele.

ma poate ajuta cinevasa dam chiulasa jos si sa vedem ce este p-acolo. La semeringuri m-as baga sa le schimb, dar de segmentare nu. Mai bine o dau.

Daca aveti alte pareri va rog sa ma ajutati.

[ManiacuV6]

In prima instanta fa o compresie sa vezi daca segmentii mai sunt buni.

Daca ai compresie buna atunci e suficient sa schimbi semeringurile de la supape. Costa intre 100 si 200 mii. Eu le-am comandat de la volksman ;) dar inca nu le-am montat.

P.S.: Ia semeringuri Victor Reinz !!! Daca iei alte firme le schimbi de pomana.

[CATAVENCU]

foloseste aditivi liqui moly....e o gama foarte larga si pt consumul mare ulei/pierdere.

Eu am testat de-a lungul timpului multi aditivi liqui moly si sunt exceptionali...ce scrie pe cutie aia face...

[georgem]

Eu mi-am schimbat simeringurile de la supape de 2 ori la inceputul anului. Prima data am pus Elring, si consumul de ulei a credcut de 3-4 ori. Ori au fost simeringurile proaste, ori au fost puse prost. Dupa care am pus Victor Reiz si consumul a revenit la valoarea niitiala, sau putin sub ea. De atunci n-am mai vazut fum albastru pe esapament, insa consumul de ulei e cam acelasi. Compresia intre 9 si 10 atmosfere pe toti cilindri. Concluzia la mine e ca e nevoie de segmentarea motorului.

Verifica-ti compresia, daca e peset 10 pe toti cilindrii s-ar putea sa scapi doar cu simeringuri de supape, daca nu probabil trebuie segmentat motorul.

[codrut]

Si unde pot face compresia? Un service, ceva mai subtire!

Cam cat costa stie cineva?

Daca aveti si un nr. de tel. ar fi perfect.

Le schimbi tu? Daca Va trebui sa le schim eu poti sa ma ajuti?

[georgem]

Nu le-am schimbat eu, am fost la un service. E nevoie de niste scule pe care nu le are oricine, in primul rand presa pentru comprimat arcurile supapelor.

Test de compresie se poate face la aproape orice service, si costa cateva sute de mii de lei, depinde de service si de cum negociezi. Chiar se face destul de usor.

[codrut]

Zi-mi si mie la ce service si cat te-a costat? Si testul si schimbarea semeringurilor.

[georgem]

Ti-am trimis prin PM detaliile.

[Gnom]

care ma ajutati cu o info:

folosesc mobile1 0w40 full sintetic. imi papa cam 150-200 ml la 500km. mecanicul imi recomanda sa incerc 0W50. nush ce sa fac ca sa schimb uleiul de proba si sa bag vreo 3-4 mil asa de proba nu am chef.

tot vad ca lumea foloseste 10 sau 15W40. la masina mea din semnatura ii prea gros?

[Reed]

Daca testul de compresie e ok si noxele sunt in limite atunci de ce se schimbi uleiul?? Dar nu am inteles de ce tu nu folosesti uleiul general recomandat de Volkswagen adica 5W-40.

[Gnom]

sa schim uleiul ca poate nu papa atat de mult ulei... :rolleyes:

[istef]

Cu siguranta ca daca vei pune 5W-40, uleiul recomandat de VW vei obtine un consum mai mic de ulei. Daca nici asa nu esti multumit, poti incerca 5W-50, care tot este mai bun decat 10W-40, care mi se pare prea gros pentru un Golf 4.

[DORU_14]

care ma ajutati cu o info:

folosesc mobile1 0w40 full sintetic. imi papa cam 150-200 ml la 500km. mecanicul imi recomanda sa incerc 0W50. nush ce sa fac ca sa schimb uleiul de proba si sa bag vreo 3-4 mil asa de proba nu am chef.

tot vad ca lumea foloseste 10 sau 15W40. la masina mea din semnatura ii prea gros?

INCEARCA 5W40 sau 5W50 ce respecta norma 503.00 (masina ta e pe benzina din ce vad). MOBIL 1 e bun !

[Gnom]

revin cu o observatie.

daca circul cu ea pana in 3000 de ture nu imi papa ulei. la drum lung unde o urc pana in 4000 cand ii cazul imi papa.

care este explicatia logica?

am completat uleiul si dupa 100 km nu a pierdut nimic. ii la aceasi zona a jojei. nu observ nici cea mai mica scadere. la drum lung scadea putin pana acuma.

[R Z F]

salut.postez aceste tabele copiate de mine.poate sunt de ajutor.

[Gnom]

multu'

credca ma bag pe un 5W4 da mai fac vreo 4.000 km pana ajung la cota de 10.000 si sa-l schimb atunci.

ca nu am cash sa schimb la fiecare 5000km uleiul... :)