The Goods On Oils

[Rolls]

Honestly you could probably run $10 black and gold 25w50 oil and change it every 2 years and you'd never see any issues until you strip the motor down 50,000kms later.

[Galois]

I'm using Motul 8100 right now and can't fault it.

Having said that, I think all this 5W40 and 10W40 being "ideal" is a little silly. Yes it's a good range but my mechanic who I trust to know what he's saying said I could run 20W50 in it no worries. This was recommended as a possible solution to queting down the lifter tapping on cold starts.

I might actually try 15W40 or 15W50 for my next oil change which should be sometime in December ie. temps will be high anyway.

What's a good but not too exxy synthetic oil that comes in 15W40 ?

Someone said a very similar thing like 20 pages ago and the response was that the engine can cope with w50 in hotter months but the worry is the more delicate parts of the turbo which won't be lubricated properly.

Honestly you could probably run $10 black and gold 25w50 oil and change it every 2 years and you'd never see any issues until you strip the motor down 50,000kms later.

+1!!! There certainly is a reason the vast majority of people use a w40. Nissan itself recommends 7.5w30 for the engine in colder Japan when the car is new, taking those two factors into account explains why 10w40 is so popular.

[siksII]

Someone said a very similar thing like 20 pages ago and the response was that the engine can cope with w50 in hotter months but the worry is the more delicate parts of the turbo which won't be lubricated properly.

Can you back that up because I dont think either is true. Are you saying you cant run a 50w oil in any turbocharged car? What is the difference in oil temps during summer compared to winter on the street the justify 50w being more suitable? (because I dont think you are talking about the track)?

[Wacky Dee]

if ambient'/intake temps are 35-45degrees Celsius (common in OZ) I'd wager a bet that during summer months the engine oil on any car especially a Skyline would be atleast a few degrees hotter.

Heat destroys oils and makes it thinner in general.

If you read on Redline's web site for example they recommend 15W50 iirc for ambients temps of 15C-50C which is about the average for Australia's summer I'd say.

quote:

All-2001 GTS & GTS-T (single turbo) (R32,R33,R34) RB25 & RB25T Eng, 2500cc, 2WD

Component Recommended Oil / Fluid

Motor Select your closest climate range. For -10°to25°C use '5W40' or 5°to35°C use '10W40' or 15°to50°C use '15W50'. (* Racing Only - use Race Oils) @ see handbook for Litres

I'm pretty sure in summer (atleast in Syd) the temps rarely drop below 20C (last summer I wished they would drop below 30C at night) so 15W seems safe as a cold temp. Now considering temps were up to 46C and these cars are kinda getting old, the W50 seems spot on too.

So yeah maybe 10W40 in winter months is about right but nothing wrong with 15W50 ..atleast in the hotter months or (hotter parts of OZ in general).

edit: oh and add to this the fact that most skylines still have the stock radiators which do not keep the engine as cool as it should be during any month. eg. my water temps were up to 98C in Summer with stock rad and 86C (ideal) after installing an aluminium dual core radiator. Hotter engine = hotter oil. Hotter oil = more thinning. There's no such thing as cold engine/engine oil during summer months, not unless you park your car in a drive-in freezer or run aircon in your garage.

[Wacky Dee]

Anyway those are just my opinions from my personal experience and understanding of how the oils work.

To sum up, if 20W50 wasn't suitable for a skyline I'm sure one of the most respected tuners/mechanics in Sydney wouldn't have said it's fine.

[siksII]

Anyway those are just my opinions from my personal experience and understanding of how the oils work.

To sum up, if 20W50 wasn't suitable for a skyline I'm sure one of the most respected tuners/mechanics in Sydney wouldn't have said it's fine.

Yeah but im sure you would agree there is a difference between fine and good.

Just because a mechanic says its fine doesnt mean much. mechanics are usually not engine oil experts and in my experience they are usually the opposite and talk out of their asses. I would recommend doing your own research before listening to most mechanics views on oils.

In relation to 20w50, I know of a Sydney car that had a freshly built motor and serviced head, the engine builder recommended 20w50. Approx 20,000kms later after regular 5k oil changes with the same decent quality 20w50 the motor was checked. The head showed excessive wear and the workshop reported it appeared as if the head had been starved of oil - they had no knowledge of the oil that had been used.

This car has now been used for over a year including a large number of trackdays with no issues that you would notice unless you inspected the head, so theres a good example of "fine"

[Wacky Dee]

first, the guy I'm talking about is not just your run of the mill mechanic ... his shop tunes lots of imports and is probably the only tuner you won't find a single negative thing said about on SAU. Secondly you're taking the "fine" a bit too literally .. he said 20W50 is not too thick for a 98 Skyline, in so many words.

Also there's a huge difference between a freshly built engine ie. as new from factory if not better AND a 10+ year old engine that's already worn in.

With all that said .. I still wouldn't put 20W50 as I'm too much of a pussy to trust one person over the countless SAU users and I don't drive my car hard at all But 15W40 ..bring it.

[Galois]

Can you back that up because I dont think either is true.

So you don't think that the w50 may be fine in the summer months AND you don't think the turbo components are the more delicate and hence harder for a thicker oil to get to? Sorry, just want to make sure I get that right.

I was just quoting, from memory, the response from earlier in this thread (at least I hope it was this thread, there are heaps of small oil threads).

In summer road temps are between 10-20 degrees hotter, don't forget road temp varies from ambient temp because the sun directly heats the road, that heat dissipates into the air causing a higher temp immediately above the road. That's why motorsports quote track temps as well as ambient temps.

That 20 degrees hotter makes a HUGE difference in the cooling rate of the radiator, which follows the simple equation q = k*A*(T2-T1), where q is the heat loss in W (or J/s), A is the area of exposure (in m2, an approximating function would be used to simulate the radiator area in contact with the moving air), T2 is radiator temp, T1 is road/ambient above road temp, and k is the complicated heat transfer coefficient, which is painfully calculated using equations taking conduction, convection and radiation into consideration. Seeing as T2 is what, 90-120oC, a change of ambient temp from 20-40 can lift the engine temp by quite a few degrees.

I have always been meaning to look up the actual viscosities the w40, w50 etc correspond to, but since I haven't yet all I can say is that a w50 at 40oC may have the same viscosity as a w40 at 25oC.

Are you saying you cant run a 50w oil in any turbocharged car?

No. What I was referring to was only talking about skylines. Nismo recommend/use w50's for track cars.

What is the difference in oil temps during summer compared to winter on the street the justify 50w being more suitable? (because I dont think you are talking about the track)?

As above.

Just for some reading,

23 Nov 2009, 12:46 PM

Post #1171

Rank: RB30E

Posts: 4,257

Joined: 29th April, 2009

Trader Rating : 0

I know nothing about oils and have no mechanical qualifications outside of , I hope , common sense and 45 years of driving experiance and DIY servicing .

After reading a shit load of posts it would seem to me the problem is one that is inherant with the RB engines and that is that the pump shoves all the oil into the top of the block/head and as the oil can't drain back fast enough so the bottom end 'can' starve resulting in spun bearings and all sorts of mischief.

Basicly what this would seem to mean in a practical sense is that an engine that should be good on 15x50 in summer and 10x40 in winter (never mind the syn v dino atm) actualy has a manufacturers spec of 7.5 x 30 so that it's thin enough to actualy drain back and not cause bottom end starvation , what a crock, 7.5 x 30 what were they thinking ?

Living in SE Qld I am lucky enough to not to have to worry to much about wildly excesive high/low temperatures,sure we get a couple of chilly ones and a few hot ones so good ole common sense says to me no floggy when too hot/cold.

As the average ambient temp is consistantly higher here that the manufacturers would have likely planned for in most of these cars I have gone for 10 x 40 Nulon Hi Flow Full Synthetic (as I posted previously) .

The price is good, the oil specification seems on the money and the results seem fine with a good hot/cold oil pressure, smooth running engine and a fuel consumption of 13.3ltr 100klms.(98 R34GTT)

I now wait with baited breath for someone to shoot down my methodoligy

^This man was on the money. DIY servicer admitting to no knowledge of oils, yet he's demonstrated more knowledge of oils than I've seen in the thread thus far (admittedly I haven't read all your posts; the thread is quite long). There's a big misconception about thinner oils always being better - this has alot to do with semi/full synthetics and the way they are marketed. Many synthetics have a wider viscosity range than minerals, which often includes a very low "winter" rating (5w etc.). Because they are more expensive than minerals and many of us have a "price = quality" perception/complex (we buy the best for our cars), their characteristics like the lower viscosities are frequently seen as ideal regardless of the application. Some are also marketed as increasing horsepower...this is true, thin oils hog less energy...but sometimes at the expense of protection where it's needed. Case in point: many 5000hp+ top fuel dragsters are running on about 25w70 mineral oil.

You need a balance between an oil thin enough to pass through the engine quickly without putting strain on engine internals, yet thick enough to actually do what oil is intended to do (think: water does not make for a good oil). This is a tough call to make and it's never an exact science (hence we have a hundred different people on here all saying a heap of different oils have done wonders for them). But as a rule of thumb, you can gauge it on A-B-C. A = age/wear/milage, B = bore/stroke/displacement, and C. climate/operating conditions.

Ignore the handbooks / owners manuals! Remember that our cars (along with many other cars brought to Australia) and their user manuals were originally designed for use in countries where temperatures during engine start up in winter are regularly below 0 degrees celsius - in these climates you need a really thin oil that doesn't thicken as easily on cold days (most liquids become thicker as temperature drops), thereby making it easier on the engine internals during startup and allowing the oil to pass around the engine quickly. In Australia there are few and far areas that see negative temperatures let alone sub 5 degrees celsius. In contrast, our warm mornings will leave your 0w/5w oil very thin for engine startup. Considering most engine wear occurs during startup and turnoff...this is where you need most protection (besides redlining the thing). Yes it needs to flow around the engine, but it also needs to do something once it's there! Also, user manuals are there for brand new cars with tight tolerances. Cars with atleast 100,000km or 15 years on the clock do not have the same tolerances they once had and they need slightly thicker oils to take up these tolerances.

In summary, for the daily driver turbocharged Skylines (most of the people on these forums), I recommend using a 10w40 semi or full synthetic oil. You can get away with using this all year round, but by all means step up to a 15w40 during summer for extra protection during the heat. Even if your car performs like a V8 it is still a small displacement engine...50 is too thick and 5w is too thin IMO.

[Galois]

In relation to 20w50, I know of a Sydney car that had a freshly built motor and serviced head, the engine builder recommended 20w50. Approx 20,000kms later after regular 5k oil changes with the same decent quality 20w50 the motor was checked. The head showed excessive wear and the workshop reported it appeared as if the head had been starved of oil - they had no knowledge of the oil that had been used.

Ahh that's so freaking scary. Good that the engine didn't need a rebuild tho. It's really hard (for those of us that do not know everything) to know who to trust. The talented individual who built the motor or countless anonymous members of a forum.

Also there's a huge difference between a freshly built engine ie. as new from factory if not better AND a 10+ year old engine that's already worn in.

With all that said .. I still wouldn't put 20W50 as I'm too much of a pussy to trust one person over the countless SAU users and I don't drive my car hard at all But 15W40 ..bring it.

Agreed. It's well known that as the engine wears the viscosity of the oils go up to compensate. I'm also on the side of the majority rules: then so many sau people say an oil's good it's certainly worth trying.

[KrazyKong]

Whoa, after reading this thread, my head asplode.

Cliffnotes time.

Car ER34 GT

Engine RB25DE Neo

ks 70,000

Engine oil - 10w30 semi syn castrol or 10w40 castrol?

Box oil - ? What do I use

Diff oil - ? What do I use

+1 to those who help

I know Galois will chip in, but Castrol hasn't got many supporters here. There are far better oils for your RB than Castrol. 10w40 is the most popular weight of choice. Semi or full synth depends on what you want to pay. But know companies like Nulon advertise they have a 100% synthetic when it's only a semi. I just noticed you have a non turbo RB, so I'm not sure if that means the turbo oils will work just as good in your car or not. Anyone?

[Galois]

Haha cheers for the tag-in kong.

I used castrol magnatec for 800km as I was doing a quick flush with "sh!tty" oil, but that one was a bit too sh!tty lol. If you ever want to feel a difference in how your car likes an oil, go magnatec for 500km then sougi (i actually went to nulon because I had some left over, still loved it tho).

Non turbos take the same oils as turbos, but since the engine isn't worked as hard they can probably take oils that turbos can't. Stick to 10w40, fully synth or a good semi synth and you'll be fine.

Remember, sougi m5000 is $30 for 5L, a grade III/V mix and has excellent detergents. It is fine for a turbo for 5000km and would be my choice for an na skyline, cheap + great + plenty of recommendation = simple choice.

Edited September 22, 2010 by Galois

[Birds]

I'm using Motul 8100 right now and can't fault it.

Having said that, I think all this 5W40 and 10W40 being "ideal" is a little silly. Yes it's a good range but my mechanic who I trust to know what he's saying said I could run 20W50 in it no worries. This was recommended as a possible solution to queting down the lifter tapping on cold starts.

I might actually try 15W40 or 15W50 for my next oil change which should be sometime in December ie. temps will be high anyway.

What's a good but not too exxy synthetic oil that comes in 15W40 ?

You might be able to run 20w50 no worries if your engine has quite a bit of mileage on it or is built with loose tolerances, but if that's the case, I would still lean towards a 15w50 for better oil flow on startup...20w50 is more for the oil burners to stop them from blowing a heap of smoke on startup.

In regards to the lifter tapping...I'm not a fan of using a thicker oil to silence them. There are a variety of causes for the noise, sometimes the lifters are starved of oil, other times they cannot retain the oil, sometimes there is not enough oil flow around the head, some engines are naturally noisy in the valvetrain. Either way, the problem is usually the lifters themselves and the only way to fix it properly is to replace them. Throwing a thicker oil in there is a bandaid solution at the expense of not running your engine's ideal viscosity. Using a thinner oil than you have been using, most of the time, will achieve the same "silencing" results but in a safer way.

Anyway, try the 10w40...I cannot stress it highly enough to people that there is no such thing as a "wrong" oil or a "right" oil, only better performing and worse performing for your car and application. Experiment! Shop around! You aren't going to kill your engine with a couple thousand km worth of experimentation.

[Wacky Dee]

I have been using 10W40 up until recently ... (motul chrono and RP) but got 8100 recently as I'm kinda saving the $$$. Anyway, on cold mornings I can hear a difference.. lifters are a bit noiser than with 10W40. So IMO thinner (cold start) oil increases lifter noise as it obviously doesn't provide the thickness required..

In any case, I think it's been established that 15W is NOT too thick for startup. Unless you happen to be one of those numbnuts that revs their engine hard and hits boost within seconds of starting (or you live in some cold-ass parts of OZ / mountains)I baby my car until engine and drivetrain is up to temp. So I'm going to be trying Royal Purple again but this time in 15W40 (one of the few good brands that has it in 15W40 apparently) IF it stops the lifters noise on cold mornings, its an added bonus.. if not, it's still a great oil and ideal thickness IMO especially with summer coming up.

Also why do you reckon noisy lifters should be fixed ? From everything I've heard and been told it's VERY common on most RB engines and is nothing to worry about..

[Galois]

Anyway, on cold mornings I can hear a difference.. lifters are a bit noiser than with 10W40. So IMO thinner (cold start) oil increases lifter noise as it obviously doesn't provide the thickness required..

That is a very interesting result mate, thanks for posting it.

Also why do you reckon noisy lifters should be fixed ? From everything I've heard and been told it's VERY common on most RB engines and is nothing to worry about..

I'm guessing he's gonna say really noisy, problematic lifters.

[Birds]

I have been using 10W40 up until recently ... (motul chrono and RP) but got 8100 recently as I'm kinda saving the $$$. Anyway, on cold mornings I can hear a difference.. lifters are a bit noiser than with 10W40. So IMO thinner (cold start) oil increases lifter noise as it obviously doesn't provide the thickness required..

In any case, I think it's been established that 15W is NOT too thick for startup. Unless you happen to be one of those numbnuts that revs their engine hard and hits boost within seconds of starting (or you live in some cold-ass parts of OZ / mountains)I baby my car until engine and drivetrain is up to temp. So I'm going to be trying Royal Purple again but this time in 15W40 (one of the few good brands that has it in 15W40 apparently) IF it stops the lifters noise on cold mornings, its an added bonus.. if not, it's still a great oil and ideal thickness IMO especially with summer coming up.

Also why do you reckon noisy lifters should be fixed ? From everything I've heard and been told it's VERY common on most RB engines and is nothing to worry about..

One of my causes as written in my post is that some engines have naturally noisy lifters, so I'm in no way saying noisy lifters should always be fixed...just that swapping for a different oil to "please" a specific part of the engine at the expense of ideal viscosity in the rest of the engine isn't something I would recommend doing. All a thick oil is doing is masking the issue by filling up the lifters with a buffer of oil that gets retained (doesn't drain out) better than a thin oil, when they should be able to run quiet using a thin oil anyway - the problem will come back in several thousand km if they are actually stuffed, you're just delaying it. The same applies to people chucking Redline Shockproof in their gearboxes to quieten synchro noise. It works wonders but the issue will be back in 15-20k, and worse.

Sometimes a thinner oil won't quieten lifters down...it depends on the damage to the lifters and whether they are actually damaged or naturally noisy. If the lifters are blocked, a thin oil will help with flow, but if they can't retain oil, it will make them noisier...which is your issue. My lifters aren't noisy running a 10w40, so if yours are then there's a good chance you do actually have an issue with the lifters (a bit subjective, would need to compare sounds and specs of engines). Fortunately lifters are one of the less urgent issues with engines, cars can go forever on them. I still advise ignoring the noise and staying with a 10w40 but if 15w40 does help you then that is not too bad of a compromise between a good viscosity and keeping those buggers quiet.

[Wacky Dee]

I agree with you on many/most of the points made but just wanted to make an obvious observation in regards to your reasoning on why noisy lifters may like thicker oil (ie. able to retain due to thicker film).

First isn't this the whole point of oil lubrication ? A thin oil that doesn't stay around for long enough to sort out minor lifter noise aren't going to provide a very good coating for the more critical parts of the engine either.. I understand noisy lifters aren't quite normal but as I mentioned earlier, it's a common issue with many imports and local cars also.

Anyway, don't wanna beat a dead horse any further ... 10W40 is the SAU recommended norm and I agree. But I'd like to try 15W40 just in case as it's like you said a good compromise (although I wouldn't call it compromise at all 15W is not very thick at all) Can anyone recommend a good semi/full synthetic oil for petrol engines that comes in 15W40 ?? Apparently the OZ distributor for Royal Purple doesn't stock 15W40 ..

Edit: never mind .. just heard back from Harold of performanceclub.com and he has RP 15W40 at $14/l. Shweeeet.

[Birds]

You're focusing too much on the lifters, they aren't a central part of the engine and there are more important areas to consider for viscosity. If your lifters are noisy because they are worn, and a thin oil does not quieten them down, this does not mean a thin oil is going to be for the rest of the engine. You have a faulty part here (assuming your lifters aren't just naturally RB noisy) causing the lack of oil retention/cushioning and the noise, so using a thick oil to quieten them down is actually doing what you fear a thin oil would do - using an oil that may not be good for the rest of your engine. As a rule of thumb, an oil being too thin is always better than an oil being too thick because the thin oil can atleast circulate between moving parts (cylinder bore, bearings, less inertia on crank) even if the shock properties of the oil aren't fantastic.

Here's a diagram of a lifter, even though it's for a pushrod, the operating principle is the same with regards to the role of oil:

When you put a thicker oil in, the cause of noise reduction depends on the kind of wear to your lifters...be it blocked passages (usually the issue when lifters are noisy on cold start only) or worn hydraulic mechanism (will be noisy all the time), oil is being retained in them and cushioning for all the wrong reasons with a thick oil. It is a good thing for oil to drain in and out (to an extent) of lifters as cleaning and disposal of waste is another important job for oil. No matter which way you look at it though, it's bandaid because your entire engine should be able to run at a satisfactory noise level using a 10w40 viscosity.

[Wacky Dee]

your entire engine should be able to run at a satisfactory noise level using a 10w40 viscosity.

It does though .. just not for the first 2 mins on cold starts heh After 2-3 mins its smooth as as ..no rattles or noise whatsoever. How does that fit in with the above observations and opinion ? (serious question, if you don't mind could you please explain) Thanks for the diagram, that's pretty cool stuff. Does anyone have one of a hydraulic (edit: SOLID actually on the NEO) rb25 lifter ??

[pipster11]

It does though .. just not for the first 2 mins on cold starts heh After 2-3 mins its smooth as as ..no rattles or noise whatsoever. How does that fit in with the above observations and opinion ? (serious question, if you don't mind could you please explain) Thanks for the diagram, that's pretty cool stuff. Does anyone have one of a hydraulic (edit: SOLID actually on the NEO) rb25 lifter ??

after 2 or 3 mins the oil has thinned out

its hard to understand but say at 20°c the thickness of a 10w40 is 100 and the thickness of a 15w40 is 120

because the both carry the same hot rating they should both thin to the same viscosity when hot, say 20

after a few mins, the oil has warmed up and is probably at about 40 (higher being thicker) so its now making its way into the lifters, filling them with oil and all is well

i'd give your engine a good flush

buy 2 bottles of nulon oil and some cheap oil (cheap as possible)

run it through for 15-20 mins, raising the revs to 2500 every 5 mins and holding them there for 30 seconds (raises the oil pressure etc)

drain the now dirty oil and change the filter, refill with sougi

[Birds]

RB25 NEO is a solid lifter? I apologise I thought it was hydraulic. The foundations of what I said still apply though, as they still require oil to keep lubricated. It's just, I wouldn't worry too much about noises because solid are almost always worse than hydraulic.

If it's only on cold starts, what I'm guessing is happening, is the passages are blocked and the oil is draining slowly out of the lifters after engine is switched off (when engine oil is hot and therefore thin enough to drain out through passages). Then when you cold start, the oil is too thick to pass back into the lifters straight away, hence they are noisy for a few minutes until the oil is thin enough to get back in. Where does thick oil come into this? Well, it takes its time to get into the lifters initially, but once there it takes a much longer time to drain out and usually stays there long enough for a cold start. By this logic, the 15w40 may not actually end up doing anything to silence them...unless on cold start the 15w acts as a sound blanket because it's thicker.

Note that this is just one scenario out of many that could be responsible for the noise. You may also have issues with oil circulation underneath the rocker cover, just another possibility. But as I said earlier we would need to compare engines and specs, of which I now know they are different anyway. If you are concerned about it I would be comparing your engine to other R34s using similar viscosities and seeing if they sound similar in levels of noise