is thicker always better? :)

[franks]

i'm running 0W-40 mobil 1 synthetic oil in my engine is this oil too thin?

asking this question because a friend who has a built up 2.2litre STi blew his engine going around a circuit and attributes this to running too thin an oil....?

edit: oil is 0W-40 not 50

[IanH]

I'm running Silkolene Pro-R 15W-50 (race oil) and most of the other oils I've seen used are around 15W-50 motorsport oils. My pressure is good (+4 whilst driving) and the temp (with the same oil cooler as you) is around 1/4 on the gauge.

When I first had it I used 0w-40 and it ran too thin and leaked past the turbo seals causing blue smoke etc.

[KamikazeR33]

franks the reason higher powered cars or circuit cars need higher viscosity oil is due to needed oil to be there when its needed eg when the oil gets damn hot. having a higher viscosity will mean the oil will be there instead of not being there if the oil was too thin

generally as far as my knowledge goes, to worry about that u should be looking at the last number, a higher number will give greater protection when its needed

u can run something like what IanH has, i did and my car ran like a dog cos it was too thick, would take longer to start and forever to get goin

just my thoughts

[franks]

good points, im going back to 15W-50

[KamikazeR33]

but the other side of the argument is how much strain a thicker oil will put on an engine compared to a thinner oil

obviously an older engine will need thicker oil because it will just blow too much by the rings

a thicker oil will put more strain on bearings, piston rings etc. but if ur fine with that then go ahead.

i think a balance between the 2 would be more justified. thats prob y nissan suggests using a 7.5w30 oil

the 30 being due to the colder conditions in japan tho

[Stirlo_GTR]

The two numbers are a representation of how think the oil is, when its cold hence your "0" and when its hot "50" which is very thick (good for keeping hot engines cool). Mobil 1 is expencive for a reason, it covers a wide range of temp.

The thickness changes with temp, ie gets thicker when hotter. There for Mobil 1 being 0W-50 will cover a wider range than 15W50. The only thing you want to be carefull of is that the oil is not too thin when starting (cold) as rb engines can develop leaks (mine is fine). On a cold mornings (Canberra/winter) you would want as thin as possible for starting so it has oil in it quick, if its too think when cold it will take ages to get up to the heads and you risk running the engine with next to no oil in it = bad. (dont flog your car when cold).

I stand by mobil 1 for road use for these reasons although I dont drive on the track (yet)and havent had much experiance with track cars, but I would assume the oil princiles are the same, but being the cars will be running hotter for longer you would want a thinker oil to cool the cylinders and stop ceasing. I belive redline make a track engine oil but I dont know its viscosity.

Things to keep in mind:

- When oil gets older it looses its viscosity (not as effective), and should be replaced

arround 5000kms in tough conditions = boost.

- If the car temp is out side the oils capability it will break down and not be effective.

- If the car is cold you shouldn't give it any till the temp needle is atleast off cold so you

know the oil is inplace.

- Oil is not only a lubricating substance but also a cooling substance.

Change your oil regularly... Car will love you long time for it..

If I am incorrect in any place's pls correct me..

[KamikazeR33]

hks make an oil, i think its 15w40 so that would give us an idea to what redline would be making.

changing oil is very important, we just retuned a tx3 turbo only to realise the oil was gone (only bout 3000kms) n it sounded like a tug boat. so we put it up on the hoist, changed it. sounded like gold again

moral : change ur oil all the time, its almost as important as insurance

btw stirlo i think u hit the nail on the head

0w50 is prob better than 15w50

hmmm wheres sydneykid when u need him?

[croat]

Does anyone here use the specified nissan oil? I cant remember the numbers and all but it is made for the skyline engine's isn't it? i thinks its '40' but not 100%. Just like to hear your thoughts....

[GZ R33]

I use Castrol Formula R - 10w60

[Steve]

The first figure in multigrade oil refers to how it passed its viscosity testing at winter temperatures, thus the W - this has nothing to do with the hot weight, which is the latter of the two figures.

So 5W50 will have the same viscosity at 100 DEG celcius as 15W50 - it is SAE 50, regardless of the 'W' rating.

The 'W' measurement is conducted to SAE standards for winter use, ie it has been tested and passed for use at 0 deg F - the lower the number the thinner the oil will be.

So 5W oil will be thinner (more viscous) than the 15W at 0 deg F, but the hot rating is the second figure. The two are measured and rated differently, so the figures dont have a direct relationship to each other in that sense.

The lower the first number, the thinner the oil will be when cold, the higher the second number the EDIT: thicker the oil will be when hot.

Stirlo_GTR how can oil "gets thicker when hotter" oils get thinner as they heat up. The trick with multi grade oils is reducing how much the oil thins so it doesnt end up thinning so much that oil pressure drops too low, and the shear resistance of the oil (which is related to viscosity) is depreciated so far it becomes useless.

If you have ever changed your oil after warming the engine, you will know that it thins as it warms.

[Bobby^]

Ok, so im in auckland nz, with a 96 s2 25t. What oil should i use? There are so many different options, and everyone says something different :S

What i need is someone to say "da da da xx-XXW" and i will be really happy and im sure my car will be very grateful.

[R31Nismoid]

Good info there Steve!

I understand some of it... Very technical that was

Might re-read it later again!

Oil, very technical thing

[Steve]

Sorry if I have confused, I just re-read my post and it doesnt make a heap of sense, so I will try and simplify

Viscosity - the higher the number, the thicker the oil

SAE test their oil for viscosity at 100 DEG celcius

W rating means it is suitable for use in winter - from what I understand this is tested by pouring oil through a specific size hole at 0 DEG celcius, so a 5W will be thinner than a 15W, as higher numbers indicate thicker oil (as for viscosity)

But remeber a 50 weight oil will always be thicker than a 40 weight oil which will be thicker than a 30 weight oil

AND the 'W' means winter suitable, not the oil weight

Hope that makes sense.

Something else of interest, is that whilst the higher the number the thicker the oil, the 50, 40, 30 etc are not actual measures of viscosity but EQUATE to ranges of viscosity, viscosity itself is measured in stokes.

Also, gear (diff, trans) oil ratings are different to engine oil ratings, for example SAE 75 weight gear oil is actually thinner than SAE 50 weight oil (at 100 DEG celcius)

Bobby^, I would suggest you speak to your local performance shop (that you trust) and ask what they recommend.

I use MOTUL 300V 15W/50, it was recommended to me by people who swear by it, and also it is used by NISMO in their cars - so it cant be bad.

How extreme are the temperatures where you live?

[Sumo]

I just change to the motul turbolight 15w-40 technosynths.... Nice oil.... Better then the fully synth Caltex oil I was using before.

Sumo

[Kinks]

0W-40 is pretty thin for the track. probably fine on the street altho the winter rating is still very thin and not needed in temperate climates. I've run 15W-60 synthetic on the track (warmer weather) and also 5W-40 on the track (cooler weather) and had no troubles at all. I only tend to do a few hard laps and then give the car a breather though... it's a daily driver after all not a racecar.

There are a few other just as important factors though - how fresh is the oil, to what level was the oil filled, and how was the car being driven. Old oil = no brainer. Level - you want as much oil as you can safely put in ie right up to the high marker on the dipstick. If you thrash the hell out of an engine for 20 minutes then your oil temps are going to climb and eventually you'll hit the point where the oil stops working. Granted this will be different for a 40 weight vs a 60 weight but if you don't have an oil cooler you shouldn't be asking that much of your car. Also are the other engine components OK with being run that hard for that long... and does the car have sump baffles

[Blitz]

Anyone else using Motul 300v? I have been running this in the GTR since I bought it - it seems to come highly recommended.

[steven]

i'm using Motul 300V racing 5w-30 on my GTT, it works quite well. And never have a problem!