More engine oil discussion.

[Jimbo2000]

thanks for the info jim

bah i'll just chuck it in and see how it goes and give it a write up here, it was either that or some royal purple whick cost the same amount......god damn expensive damn cars bloody thing grumble grumble

[2rismo]

I use BP Visco 5000 Synthetic.

It magically arrives at my house in the dead of night in 20L drums from the oil fairies and is a 5W40.

Isn't that how ALL oil is purchased?!?!?

lol.... free stuff rocks... almost makes up for having to buy parts at 10x the price.

Adrian

[Guest RedLineGTR]

whatevers in your budget i say...

[R31Heaven]

Every one keeps talking about thicker oil when the number goes up, the oil is not thicker per say, the High number is the viscosity or what tempreture that it brakes down and loses its protection. The lower number is the better to get how thick or flow rate when cold so the lower the number the better it flows when cold. This is what turbo motors need protection at start up. Mobil have 0-40 but not many areas have constant 0 degree mornings so a higher number can be used. And always use a good Synthetic that has less ash and aditives to hold its viscosity as they cause wear on the engine. Ie Mobil 1. No I am not a salesman for Mobil :headspin:

[JimX]

Every one keeps talking about thicker oil when the number goes up, the oil is not thicker per say, the High number is the viscosity or what tempreture that it brakes down and loses its protection.

No, it's how thick or viscous the oil is at cold (former) and hot (latter) temperatures.

[R31Heaven]

yeah the oil starts off at a thickness/Viscosity and as it gets hotter thins out or looses its viscosity.and the higher numbers is the temp that it starts to loose its thicknes/viscosity

A good document to have a read of

[Bleach1]

I have been using Mobil 1 0w40 for over a year now and the car has never missed a beat and the oil pressure has always been perfect. When i got the car the so called "import specialist" i baught the car from had been using shitty penzoil in all their cars. One of the first things i did was change to the mobil and noticed the engine revving much better. I dont really thing wear will become a problem with the thinner oil either.

[JimX]

R31Heaven I'm not sure if you are describing the same thing. The numbers in the weight rating do not translate directly into temperatures. The cold number is the weight at 0 degrees F (-18 degrees C) and the hot number is at 210 degrees F (99 degrees C).

The reason for the split numbers is for multigrade oils. Not all oils are like this, but the ones we use in our cars are. All oil thins as it heats up. The oils with the higher hot weight number just means it doesn't get as thin as an oil which was the same grade of the lower number.

I'm not sure if this is what you were trying to say, but "the higher numbers is the temp that it starts to loose its thicknes/viscosity" is incorrect. The temperature of what, anyway? The coolant or the atmopshere or the oil itself? There's no way that engine oil only goes up to 30-60 degrees. It's several hundred degrees in the combustion chamber.

[R31Heaven]

Excatly isnt confusion grand? here is more of a info below.

Viscosity is a measure of the "flowability" of an oil. More

specifically, it is the property of an oil to develop and maintain a

certain amount of shearing stress dependent on flow, and then to

offer continued resistance to flow. Thicker oils generally have a

higher viscosity, and thinner oils a lower viscosity. This is the

most important property for an engine. An oil with too low a

viscosity can shear and lose film strength at high temperatures. An

oil with too high a viscosity may not pump to the proper parts at low

temperatures and the film may tear at high rpm.

The weights given on oils are arbitrary numbers assigned by the

S.A.E. (Society of Automotive Engineers). These numbers correspond

to "real" viscosity, as measured by several accepted techniques.

These measurements are taken at specific temperatures. Oils that fall

into a certain range are designated 5, 10, 20, 30, 40, 50 by the

S.A.E. The W means the oil meets specifications for viscosity at 0 F

and is therefore suitable for Winter use.

The following chart shows the relationship of "real" viscosity to

their S.A.E. assigned numbers. The relationship of gear oils to

engine oils is also shown.

Multi viscosity oils work like this: Polymers are added to a light

base (5W, 10W, 20W), which prevent the oil from thinning as much as

it warms up. At cold temperatures the polymers are coiled up and

allow the oil to flow as their low numbers indicate. As the oil warms

up the polymers begin to unwind into long chains that prevent the oil

from thinning as much as it normally would. The result is that at 100

degrees C the oil has thinned only as much as the higher viscosity

number indicates. Another way of looking at multi-vis oils is to

think of a 20W-50 as a 20 weight oil that will not thin more than a

50 weight would when hot.

Multi viscosity oils are one of the great improvements in oils, but

they should be chosen wisely. Always use a multi grade with the

narrowest span of viscosity that is appropriate for the temperatures

you are going to encounter. In the winter base your decision on the

lowest temperature you will encounter, in the summer, the highest

temperature you expect. The polymers can shear and burn forming

deposits that can cause ring sticking and other problems. 10W-40 and

5W-30 require a lot of polymers (synthetics excluded) to achieve that

range. This has caused problems in diesel engines, but fewer polymers

are better for all engines. The wide viscosity range oils, in

general, are more prone to viscosity and thermal breakdown due to the

high polymer content. It is the oil that lubricates, not the

additives. Oils that can do their job with the fewest additives are

the best.

Very few manufactures recommend 10W-40 any more, and some threaten to

void warranties if it is used. It was not included in this article

for that reason. 20W-50 is the same 30 point spread, but because it

starts with a heavier base it requires less viscosity index improvers

(polymers) to do the job. AMSOIL can formulate their 10W-30 and 15W-

40 with no viscosity index improvers but uses some in the 10W-40 and

5W-30. Mobil 1 uses no viscosity improvers in their 5W-30, and I

assume the new 10W-30. Follow your manufacturer's recommendations as

to which weights are appropriate for your vehicle.

Viscosity Index is an empirical number indicating the rate of change

in viscosity of an oil within a given temperature range. Higher

numbers indicate a low change, lower numbers indicate a relatively

large change. The higher the number the better. This is one major

property of an oil that keeps your bearings happy. These numbers can

only be compared within a viscosity range. It is not an indication of

how well the oil resists thermal breakdown.

Flash point is the temperature at which an oil gives off vapors that

can be ignited with a flame held over the oil. The lower the flash

point the greater tendency for the oil to suffer vaporization loss at

high temperatures and to burn off on hot cylinder walls and pistons.

The flash point can be an indicator of the quality of the base stock

used. The higher the flash point the better. 400 F is the minimum to

prevent possible high consumption. Flash point is in degrees F.

Pour point is 5 degrees F above the point at which a chilled oil

shows no movement at the surface for 5 seconds when inclined. This

measurement is especially important for oils used in the winter. A

borderline pumping temperature is given by some manufacturers. This

is the temperature at which the oil will pump and maintain adequate

oil pressure. This was not given by a lot of the manufacturers, but

seems to be about 20 degrees F above the pour point. The lower the

pour point the better. Pour point is in degrees F.

% sulfated ash is how much solid material is left when the oil burns.

A high ash content will tend to form more sludge and deposits in the

engine. Low ash content also seems to promote long valve life. Look

for oils with a low ash content.

% zinc is the amount of zinc used as an extreme pressure, anti-wear

additive. The zinc is only used when there is actual metal to metal

contact in the engine. Hopefully the oil will do its job and this

will rarely occur, but if it does, the zinc compounds react with the

metal to prevent scuffing and wear. A level of .11% is enough to

protect an automobile engine for the extended oil drain interval,

under normal use. Those of you with high revving, air cooled

motorcycles or turbo charged cars or bikes might want to look at the

oils with the higher zinc content. More doesn't give you better

protection, it gives you longer protection if the rate of metal to

metal contact is abnormally high. High zinc content can lead to

deposit formation and plug fouling.

[JimX]

R31Heaven, that's a better explanation I had a feeling that was what you were trying to describe, but the way you worded it it sounded like you meant the second number was the temperature in degrees C at which the oil started to break down. But then you said that it's an arbitrary number and described the viscosity better, which is the same as what I understood it as being. So it was just misunderstanding on my part. Sorry 'bout that!

[BuzLightyear]

Hey JimX - I think it comes down to the clearances argument, i.e. Jap engines like ours having closer tolerances. I think the 5W30 is fine all year round.

Here's a thought - the Mazda Tribute runs Mazda's 0W20 (not a mis-print), and it produces about 140kw.

[R31Heaven]

If I worded it properley the first time it would have made things easier :Bang:

[Bassit]

my opinion.

10/40 minimum

(if you must 10/30 synthetic minumum for winter)

15/50 for track.

also, if car compays had a choice of using 10/30 or 10/40 weight oil, then they would recommend the 10/30 wreght oil. why? coz 10/30 gives better fuel economy, thus lower emmissions (very important in the USA laws), more HP.

also these recommendations are for NORMAL driving conditions. i.e rev to 3500rpm then change gears. but who here drives like that

so for me 10/40 is absolute minimum for me.

jmo

[Ash]

my opinion.  

10/40  minimum

...

15/50 for track.

...

so for me 10/40 is absolute minimum for me.

jmo

Just today i put 0W-40 (Mobil One) In my car and it runs fine, maybe even better when cold than my old Mobil One did (5or10W?-40) (whatever the one you buy in the shops is)...

i have noticed that when cold the oil pressure is much lower than my older oil. when cold the old oil sat just above the 4 now mine sits just above the 2. the oil pressure only changes slightly from cold to hot.

the engine is running fine, isn't burning oil or anything

i have a 1997 tho, so it may have les engine wear than other R33's...

Anyway thats my 2c.

[JimX]

The cold weight number isn't too important for our cars. Fifteen is probably a bit too thick, but there are still people running 15W-XX oil and don't seem to have any problems. They would probably start having problems if they lived in the mountains in the winter though.

I've never heard of anyone else in here or anywhere else having problems with 0W-XX to 15W-XX oil in their car. The hot weight number is the important one. Unless you like to flog your car when the engine is cold, then the cold number might start becoming important.

[PHaT MR30]

I remember the last thread.. probably cos i started it, but i recall someone saying they got Mobil 1 and said it was ok, then switched to Motul 4100 (i think) and said they had less of a pressure drop etc and the car ran better and all

wanting to know opinions on this as i am tossing up between Mobil 1 5-50 or motul 5-40 both on special at Autobarn + i get a discount

a mate put the mobil in his R33 and said its good, i really wanna go the motul though just from what i have heard/ the success i have had with it in the past in my dirt bikes etc

by the way i have a mild RB25DET (now, didn't last post)

[JimX]

PHaT MR30, I've got the Motul 5W-40 in mine now and the car runs beautifully. I don't know if it's related to the oil change, but idling has improved a lot recently. At least I can deduce that it doesn't *harm* the idle at all, even if it doesn't improve it.

How do you get a discount from Autobarn? Maybe we should do a group buy of some good oil.

[PHaT MR30]

sorry can't do the group buy, a mate works there and just gives me a discount when the boss isn't looking,

but the bonus is motul on special $55 minus say $10 disc + at the moment you get a free Motul cap!

see my problem is recently my oil light came on while pulling up down hill at and intersection. i pulled over immediatelly and left the car overnight, checked it the next morn to find it below the low mark, now my sump is a bit mashed up from importers, so i reced out and got the oil i thought it had in it Fuchs 10-30, topped it up to get home (200km from home) i topped it up with full synthetic and checked with the oil can i had at home to find its mineral based, so now i got to flush engine out ( got some industrial engine flush that you can't buy off the shelf). im thinking buy oil now save $$$, car is off the road right now so i get a sump and change that too then i should have to worry about a thing, changing water pump and timing belt too

sorry to be a post hog

[JimX]

I wouldn't run any sort of engine flush in my Skyline unless it was absolutely chock full of crap. Running a few thousand km on mineral oil isn't enough to warrant it.

Just drain the mineral oil and run a good quality full synth. They have their own flushing compounds in them (detergents), but in a safe amount and at the correct ratio to not disolve the rest of the oil in your engine.

[PHaT MR30]

yeh agreed, but it has a mix of mineral and synth

so maybe if i just use a bit to thin so it completely drains out