good stuff

Number 1 rule for oil in anything engine or gearbox is to replace it regularly. Cant be emphasised enough. Like it has been said before which i totally agree with, 5000kms for oil is the go and every 10000kms is when to replace a filter. You can replace the filter every 5000kms aswell but there are no major advantages but certainly wont hurt.

Second thing you need to realise is what is best for a car and what is recomended are two very different things, with the latter designed to look attractive with respect to costs, availability and time. Subaru now has 12000kms servive intervals recommended for their wrx. If anyone was to drive that car hard by changing the oil every 12000 would result in drastic decline in power and engine life would suffer. The ej and sr engines are both marvelous motors and the sr is probably thougher, but when mr.average goes to compare cars and see he doesn't have to service his rex that often he thinks time and costs are recuced. Which they are and would work fine if he drive it like mr.average which no one here does. 5w30 oil is recommended by nissan because: japan has low maximal temperatures and high pressure in relation to most countries and autralia is at the other end of the scale of the places that get the sx. 5w30 is readily available and works very well for the conditions there. Here, despite what you say and think it is not ideal and certainly not for had driving in hotish areas. Nissan also recomends to use their oil (cheap mineral based castrol, they also say to change the gearbox oil at 40000kms (i think) and i felt gearboxes on other s15 which is gritty and has poor action. I have changed my gearbox oil every 10000kms and despite running well over 200kw atw is smooth as silk)

I personally advised subaru a while back about the oil they were using in their wrx from the factory which was a 5w30. In the run in period the cars were using about 4 liters of oil in 5000kms. The oil was breaking down and burning to quickly. They now use a 10w40 in most cases which oil consumption is now minimal. One would think these so called experts from japan would know.....

The bottom number like the 0w or 5w is a code that was developed by the society of automotive engineers (SAE) to rank the oils flow characterists in cold conditions. At turbo needs a low co-efficient here and 0w and 5w are both good. The reason why it needs this is to provide instant protection to the turbo at start up. Turbos are vulnerable to damage when they are cold and oils dont work well at all when cold. 0w and 5w get to opperatinal temp fast. The second advanatage with a 0w or 5w ect is that it flows and moves well through the oil ports and this enables less strainon pumps and seals and also means that less energy from the engine is being used to move this oil.

The last number the 40 or 30 or 50 ect ranks the oils flow characterists in hot conditions. The lower the second number the more suseptiable it is to thermal oxidation. The higher it is the better is resists break down. A 0w40 works better than a 5w30 because both numbers are on either side. As is the 5w50. A 5w30 breaks down fast and in that sense means that its life in the engine is limited. The reason oils like 25w60ect are used is for big bore high hp engines like 6l v8/10 pushrods where they have massive pistons strokes, high hp and hard revving. The bigger the stroke the more sheer stress is placed on rods and bearings from inertia and internal mechanical momentum. Thin oils dont maintain the required 0.00001 oil film thickness needed for high stress. Therefore for sx or wrx's that are pumpng out alot more power then something like a 10w40 or 10w50 is better is a 5w should be fine.. Racing oils are usually a 15w50 and they work well in extreme heat and mintain their performance ONCE they are up to temp. Using these viscosities needs them to be warm before giving some stick. So yes you better believe that capacity has ALOT to do with is because the smaller the capacity the smaller the stroke (in general) and the smaller and tighter the oil ports.

Tri synthetic means that it uses there base stocks which are aromatic olifins and mistures of simple alkenes and alkynes. It is not more pure, i dont know where you got that from. Being 100% synthetic means just that regardless of using 1 or 3 base stocks.

I have never at anytime with any engine seen clogging up because of viscosity related problems. It purely and simply doesn't work like that. Clogging is usually because of contamination from water or other oils (minerals to race synthetics do this chronically). Most certainly will never happen if the oil is changed every 5000kms.

The reason why the engine looks so good after that time by using the 5w30 is for no other reason than its been changed regualrly which like i said is the golden rule.

So....having a 30 weight miltigrade oil has limited use and offers limited protection in comparison to the other types mentioned. Saying that it leaks past rings is totally untrue because this happens when the oil has a low flash point which most good synthetics are high.

i just hope i dont loose people with the chemistry because i have done that before. Thin oils have thinner characteristics at low temps compared to thick oils - obvisouly. 0w and 5w are both fine. This is good because it means it will circualte with ease at cold temps and start up. The reason why it good for a turbo is because it allows for better and more efficient spool up. It also gets to oppertional temp quicker. A fluid with a high density has a higher specific heat capacity (with al things being equal) which means it takes longer to store heat. Oils dont like being cold. When the car has warmed up the turbo has not, or not that well i should say. It takes time when the car is on boost for the turbo to get up to temp. Thin oils are quick to respond (matter of seconds) thick oil are not (upto minutes). That time is a killer for turbine wear. But no one hear has issues with the lower viscosity (except the 25w dont know what on earth is going on there) So 5w30 is fine for that.

Where the problem comes in is the 30 bit. Its to low. That means the oil molecules will begin to dissociate upon thermal energy past its flow rate. This is oxidation or break down or in my terms the lose of electrons from outer shells in atoms. Therefore when the engine gets hot, the break down of the oil begins to occur and happens quickly. This means its life in the engine is limited. Thicker oils have larger aromatic hydrocarbons and stonger carbon to carbon bonding between the alkanes. Basically its a bigger molecule. Hydrocarbons are just that - hydrogen and carbon molcules and they start off simple gases like methane CH4, to liquids like octane C8H18 up to waxes as high as C80 ect and then into tars. The higher the carbon content the higher the viscosity and the harder it is to break down into simpler forms. We know that butane (C4H10) from a cigi lighter burns easily cause its small but a larger one like petrol (which is a mixture of octane, pentane and hexene) is less volitile and then diesel is less flamable again cause its bigger - feels greezy between the fingers. Gas is better than petrol, which is better than diesel which is better than oil ect...with respect to breakdown or flamability and thus resistance to oxidation.

So....the thicker, the heavier, the more resistant to heat, the longer it lasts. The sr and ej and 4g engines have pretty small sumps and small oils ports. They need something that circulates easily. Presure is related to density and corss sectional area of the passage in which it flows and density is related to viscosity and x-sectional area is related to port size. Sucking water through a straw is easier than sucking honey.

When the temps get to high the 30 oils is out of its range and it starts to become ineffective. I can hunt down some mass spectrocopy plots and titration curves comparing the multigrades we use for different tracks and requirements for the f1 engines. It shows how as temp rises oxdation occurs at a rate of 0.056m/mol per Kelvin. This is for the 'special' oil in the race engines, the trends would be the same in road oils as well.

Also, the stoke on a 2L motor is quiet small. This is why our engines rev to 7000rpm and most pushrods v8 go to 5500. The longer the stroke of the engine the more stress occurs on the bottom end bearing from internal inertia. Like dropping an object from two fifferent heights and each will hit harder depending on height and load (revs). Thin oils find it hard to maintain the thin film lubrcation on bearing when the stress becomes high. So if the engine is working hard for long times or has massive power and or long stroke then the oil needs to become thicker - what resists spreading easier out of grease and wax - both HC's but wax is thicker. Thicker oils resist destortion upon movement.

Hopefully that makes it clearer - but quiet possibly makes it hard to follow but i tried to relate it back in lame terms.

I have no prob in people expressing views ect and their thoughts, but its when i get called a f*ckwit and retard about my knowledge on something that has been my life is a hard pill to swallow.

ll these factors are dependent on several factors including ambient temp, pressure, fuel types and O2 saturation. The specs on the sr engine with respect to it running i cant tell you. I dont have any gauges except a boost, but i could sourse this the workshop.

Oil characteristics are also dependent on even more factors, right down to the metal components. But, one primary indicator is the flash point of the oil. One could expect a flash point of 225, 234 and 245deg cel for 5w30, 0w40 and 15w50 respectively (these are off the top of my head and are for mobil 1 products so it may vary slightly). This tells you the temperature at which they ignite. So it also gives an indication as to how well they resist breakdown from heat. It is impossible to relate an sr engines characterists back to the chemistry of an oil because there are two many variables.

Also, the sheer reistant abilities are also important. At 100deg cel the rating are 11.3, 13.4 and 16.8 for 5w30, 0w40 and 15w50 respectively (again from memory with mobil 1 products). This tells you how well this oil maintains thin film resistance under a given load at 100deg cel. 11.3-13.4 is very significant indeed and 40 more kw through the rods and low end learing will create this.

Also you cant compare opperating temps with oils flash points. The heat from friction between rings and cylinders and bearing is way higher and again veries on many things.

With your question on the turbo "and we still have the issue of the oil not needing to be thin on startup to "protect the turbo" cuz you idle for 3-4 mins to warm engine up, then drive slowly out the driveway, slowly down the street, then let it rip, by this time turbo and engine are nice and warm :)" - not quite true. Engine oil is NO WHERE NEAR upto temp after a few mins. Coolant yes, oil NO. Even a thin oils takes time. So whilst the oil temp is ok for bearings and rings, for the turbo its not. The thinner it is, the quicker it will get up to temp.

5W30 is not my issue. I have been saying all along the 0w40 is better and i have been telling all along that your unfounded statements that it does this and does that is total bs. I have shown you why these are better. I'm NOT going to give raw data (as if you would have any idea what it means anyway) to you or anyone over a forum. That would look brilliant on shell or castrols desk monday morning as would the sacking of me. I have shown point blank that these type work and protect better than the 5w30 and i have explained in chemical and physical terms why. I have also explained why the 0w40 is better and why both 0w40 and 5w50 are better. And like i said i can well and truely. And 99% of all these so called expert oppinions that you have been giving (where someone consequently wastes there money based on your advise) is all concocted bs. I have shown what you have said is wrong, i'm not going to provide raw data for the obvious reasons and the fact it will take a while to get it, not to mention you'll come back and ask " what brand of conical flasks were used and um, did you use a cigarette lighter or match to light to bunsen" and so on and so forth.

At the end of the day use what you want - crisco, extra virgin olive oil whatever i dont care. I Have gone into to much detail about all selection and all you going to do is keep chasing your tail and try to claw back some credibility that youv'e pissed into the wind. I have explained, they are the facts, i know what i'm talking about and i have the experience and knowledge to back it up, if you dont accpet it and cant then thats your problem, dont make it mine. And manus, i'm sure there would be arguments with montoya about the best way to brake into turn 1 at silverstone and NASA on how to send a rocket into space.

BTW, i would be interested to know what data you have about an SAE 50 mono visco oil clogging up wells, thin oils getting past rings and metal shavings clogging up filters.

15w50 is the general viscosity of competition engines, what i would recommend for most for track work. 15w60 is pretty full on and probably more suited for the drag GTR's that pump over 1000hp. Chemosynthesis i presume means 'chemical - synthesised. Sounds pretty wizbag but just means made by chemical reactions or in normal language - synthetic.

i was wondering if any of what i have been saying was to be put to use.
- i'm over and out with explaining and giving info to you. There is no doubt you would argue with a plastic surgeon on a facelft technique, let alone a chemist from mobil and mclaren on oil use and application. Use what you want. You were plain stupid coming out so strong from the start saying so many wrong things. If you were to just state you use this because of the manual and it works well then its all good. Saying these types dont work because of certain reasons and then argue me with on my profession is rather extraordinary. 200lm of old oil. Big deal, it just means the new oil will have a small quantity of carbon and thats about it. If you have ever watched mechanics do their work, most of the time the old oil hasn't even finshed draining before the plug is back and the filled. A whilst i respect mechanics immensely, they are not chemists or engineers and their profession does not entail physical fluid dynamics and organic chemistry. Mine does. Go to some of the major performance workshops around australia and see what they service their clients road cars with including sr's and ej and rb's - none other than everyday mobil 1 0w40.

However, if anyone has any other questions about engine or gearbox oils or fuels then i'm more than happy to help them out.

I presume no turbo. You could use anything like m1 5w50, agip sint2000 which is a 10w40 from memory or the equivilant from catrol r or shell helix ultra. You could go into the elfs (their race oils) but they are around the $175 for 5L and they dont have alot of the corrosion inhibitors and anti foaming agents you need.

- i dont know that make of oil to be honest but most brands these days are very good so i dont doubt it works well. Like car companies, most oil companies are owned by others so the quality control is tight. Synthetics are better because they last longer and resist oxidation ALOT better than minerals. Semi-synthetics are gernally a 80%mineral and 20% synthetic blend. So they still work very well like the mobil synth s or shell helix plus. I would be working towards a 10/15w50. It just flows that bit better through the engine than a SAE 20. You will also find minerals burn easier than synthetics so consumption might go up a bit.



Changaz - The noise your hearing can be one of two things. The rocker arm on the valve which means the clearance is out or the hydrailic valve lifter is gone or has air in it. Thin oils tend to make the problem worse. Try a 10w40. Its because the thin oil is immersed between the metal surfaces easier which means the contact between points is sudden and not gradual. Think of it like jumping on carpet or a thick matress.

For your standard gearbox you must get a GL4. Something like mobil XHP is a good start. You cant use a gl5 like redline and motul and castrol syntrax ect like most people here do. It promotes wear and a gritty feel. The problem is not to many companies make a good gl4 because 99% of boxes are a gl5 like the gtr and rex ect. The diff is a gl5 though. So if you can sourse a good synthetic gl4 then thats the go. I have used an additive in the gearbox of the s15 and my RM250 called bitron that works very well. I have changes the oil in by gearbox every 10000kms and the action is glass smooth. I have felt others that have not been done at say 30000kms and its notchy and outright shocking.

The viscosity of the oil between synthetics and minerals is not an issue and has nothing to do with why they are better - viscosity is viscosity regardless of whats in question. It all related to the molecular composition of the two basestocks, where synthetics are "harder" and cause the glazing effect with new metals because they haven't keyed in. The way they key in is from thermo adjustament, and synthetics cause a more rapid transfer. Minerals are "softer" and are more forgiving with the metals and allow for a more raw type of lubrication, where as synthetics tend to run more clean which is not exactly what is needed for new engines. Porsche use different metal components for their engines like and these metals dont suffer from the same problems that traditional compositions do. All the information is in that report i posted, and i can tell that stevo has read it . But i was wondering how long it was going to take for people to start asking questions that had been answered......

The main change from that tim ein the car is the oxidation of the hydrocarbons and the accumilation of carbon itself in the oil. When the oil gets hot, the chains break down and its looses its ability to maintain proper film thickness over rotating journals and immobile surfaces and its wont dissipate heat aswell. With that time, there is a build up of water and swarf, but the latter is such a non-issue like i was saying, because the metallurgy and filters is so good, its not worth thinking about. The other problem is carbon build up from fuel combustion. The more carbon, the less affective it lubricates because it washes the film away from the bore. That is partiularly a problem with engines with rich fuel tables.

The whole thing is pretty simple....good oil every 5000kms and filter every 10000kms. Doing anymore wont achieve a thing except depreciation of the bank balance and some kind of personal satisfaction i guess.