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agreed - when choosing an oil for your motor you definitely need to be aware of the condition of your motor and the conditions the motor will be subject to

i would also accept for fact that there has been more engine failures due to poorly-selected lighter weight oils sheering down as opposed to failures of higher pressure / oil pump failure due to heavier weight oils being used

i will add that the only application where i see a 50w performing better than a good quality 40w is during prolonged extreme temperature applications - like track days / racing - on the street i think a well versed 40w or even a 30w will perform more efficiently lubricity wise for most applications / motors - the exception being internally built motors which again have differing tollerances

are you able to disclose what you have learned from your trial and errors between different weights - as well how did you find your oil pressure and temperature reading between say a 40w and a 50w? being a 15w cold did it take longer to reach optimum temperature and pressure?

MSR - who is a premier Subaru tuner and engine builder recommends a diesel mineral 15w-40 which is quite thick - he recommends that these cars are warmed up prior to being driven and driving should be very sedate until the oil pressure has fully stabilized - usually after 20 mins of driving

in saying that i have seen more well performing UOAs on thinner oils than i have seen in heavier weights - across a wide board of weather conditions / cars

One of the issues of making blanket recommendations is that every engine will be different. A tighter engine will run happily on ‘thinner’ oil such as a 0W30, but if you’ve got an engine with loose clearances then it will reduce bearing life. The engine failure thread is littered with examples of RB engines spinning bearings. This is not scientific of course, but most examples seem to be running oil on the thinner side of the spectrum.

i would have to disagree to an extent here, is i think although many oil manufacturers are moving to reduce costs in the manufacturing process of their oil - there are some manufacturers who are continually bringing out oils to further exceed and prolong any motors requirements (im talking about the fuel injected age ofcourse - not the carby era)

Manufacturers like Motul / Amsoil / Redline / Royal Purple are a few that i have seen further improve oils that would further benefit our engines - with the introduction of many new Esters, on top of Molybdenum and Zinc - i really think oil is as good as it has ever been for fuel injected cars

On top of this, there are other aspects to consider such as additives missing from newer oils that may be necessary for the long term reliability of older engines (e.g. zinc and phosphorus).
Edited by squareznboxez

I think another thing you all need to keep in mind is that the manufacturer recommendation is for maximum economy on a COMPLETELY stock motor. Start modifying and that goes out the window.

Squarezandboxez: I read through some of your source material, and it's still a lot of opinion. The MSDS for example you cite isn't even off the Castrol website! I did however look it up on there, and it made no mention of the additive package used. I also think you're drawing a bit of a long bow to say that the prescence of an organic based compound in the additive package is indicative of it being hydrocrack rather than PAO base stock.

In regards to weights, I can tell you that the 25w50 made the lifters rattle terribly for the first 5 minutes or so on a cold start, whereas the 10w60 is momentary (hydraulic DoD lifters need oil pressure to not tick)

I'm not sucked in by the marketing hyperbole about 'titanium fluid strength' and such things either.

The only real expert opinion / testing I could find was that of Steve from Mainlube (who also manufactures a true Group 4/5 racing oil, as used by some rather big name workshops) who only recommends the Castrol 10w60 over anything else for those who can't afford to buy Mainlube, for any modified LS cars. I can't find the actual Filtergram or I'd post it, just awaiting my UOA kit to send off to find out how the Edge performs with a 10000km service interval.

are you able to disclose what you have learned from your trial and errors between different weights - as well how did you find your oil pressure and temperature reading between say a 40w and a 50w? being a 15w cold did it take longer to reach optimum temperature and pressure?

My cooling system is 100% stock R32 GTR so it still has the oil/coolant heat exchanger. Therefore the oil gets up to temperature quite quickly - around 10 minutes with light throttle (depending on the ambient temperature). Oil pressure is obviously very high on a cold start but settles down within a few minutes. Amongst others, I tried a 10W40 (noisy on a cold start, lowish oil pressure) as well as a 10W60 (noisy on a cold start, highish oil pressure). The 15W50 seemed to be happy medium with little cold start noise (note I only drive the car on some weekends so the car can sit unused for a while) and oil pressure readings through the rev range that were only slightly on the high side of the factory specifications. Oil temperature is fairly stable at just above the 90 degree mark, although it can get up to 100 degrees under certain conditions.

Note it is not an appropriate viscosity oil if you jump in the car and give it wide throttle openings straight away!

MSR - who is a premier Subaru tuner and engine builder recommends a diesel mineral 15w-40 which is quite thick - he recommends that these cars are warmed up prior to being driven and driving should be very sedate until the oil pressure has fully stabilized - usually after 20 mins of driving

Interesting, they probably build engines with that viscosity oil in mind. I would run a 15W40 if I could get a quality easy to find oil in that grade.

I've just sent off oil from the last oil change to be analysed. I'll post the results when I get them if you're interested.

It's a good oil, you won't be disappointed.

I managed to source a 20L drum for $120 through Repco, but then I had to buy the pump for it...

asif use a pump...pour it like a man..with no funnel..

or fuly automated like this if you own a honda :P

59609_10151349817256499_902828608_n.jpg

{that drum cost me 150...my ute is 80 for 10l...if the rating is right on the gulf would be great}

but seriously why you need a pump..usualy they come with a little tap you screw in the bottom....i got stacks of taps if you need em

120$ is a bargain tho..is it SN rated...or CI what number??

Let me know what it's like and how much you can get it for, after running the Sougi 6000 for 4 years I am a GW fan for life now... :)

Couldn't find it in my local repco or Autostooge so forked out the extra for Castrol Edge 10w60

Will change oil next weekend.

I want to do it after using some subaru upper engine cleaner - even though it's an RB25

Edited by TTT

how does retarded timing cause extra heat?

and does advanced timing cause lower temps?

Old post but retarded timing means that lots of the energy is lost as heat out the exhaust port, advanced timing means more of that heat is converted into mechanical energy.

MSR - who is a premier Subaru tuner and engine builder recommends a diesel mineral 15w-40 which is quite thick - he recommends that these cars are warmed up prior to being driven and driving should be very sedate until the oil pressure has fully stabilized - usually after 20 mins of driving

I'm coming up to my first oil change since buying my Skyline (1994 R33 GTST). What's the opinion on Caltex Delo 400?

It's a mineral based fleet oil. I've used it on diesels, turbo-diesels, carby and fuel injected NA engines and even in my bike. So far Delo has been the bees knees for me; and at $75 for a 20L drum it is well budget. Is it a good idea to use Delo in a RB25DET?

Mileage: nfi (still running smooth, plenty of compression)

Boost: 7 psi

Drain interval: 5000 km

I drive it as a daily

My used oil analysis came back.

post-92407-0-89056400-1355370725_thumb.png

http://www.roktex.co...ublished=527460

Nulon 15W50 with around 6 months (April to October) and 3500 km on the oil. Looks alright to me. I'm surprised at the lack of fuel dilution given the generally rich tune.

No idea where the titanium would have come from though... One of the downsides of having no idea what is inside the engine.

Edited by BuuBox

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