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Urgant Question. R34 Gtt Rb25det Changing Oil?

skylinessuck

By skylinessuck,
in General Maintenance

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Birds Grand Master

Birds

Posted
Posted

Yuck, hideous viscosities! Really shouldn't be running more than 10w40 in an RB, 15w50 at the most if you do a bit of track work or have loose/worn engine tolerances and blow smoke on a 10w40.

llama_au Grand Master

llama_au

Posted
Posted

Why would I be kidding? I run it on my RB25DET & SR20DET and both engines love it.

10W40 seemed to 'go missing' on my SR which see's massively high revs and reasonably high oil temperatures. 15W60 keeps my RB happy and quiet.

VSPECT Mentor

VSPECT

Posted
Posted
Yuck, hideous viscosities! Really shouldn't be running more than 10w40 in an RB, 15w50 at the most if you do a bit of track work or have loose/worn engine tolerances and blow smoke on a 10w40.

thought you only blow smoke due to the car running rich...is it a different smoke you blow with bad oil?

llama_au Grand Master

llama_au

Posted
Posted
are they very old engines?

The RB25DET is 12 years old, not rebuilt and ~150,000km old. The SR20DET is 13 years old, not rebuilt and ~90,000km old. Neither blow smoke. Both have excellent compression and make the power I'd be expecting from them.

I just find the thinner oils break down far quicker and end up thin and watery by the next oil change. The slightly thicker oil gives me a quieter engine and I drain almost exactly what I put into them out at the next oil change. A good number of 10W40 oils contain a lot of friction modifiers to achieve the desired viscosity, they're not fantastic for the engine.

Harey Veteran

Harey

Posted
Posted
to answer your question i use castrol edge 10w-60 since its been recomended by my mechanic...

Lots of people on this forum seem to be using this oil in there RB's, including some pretty serious setups.

The oil thing has me sooo confused.

Birds Grand Master

Birds

Posted
Posted
thought you only blow smoke due to the car running rich...is it a different smoke you blow with bad oil?

That's smoke from unburnt fuel when the car is running rich. Yes, it is a different when you burn oil, and it's caused by worn seals/tolerances...e.g. piston rings or more commonly in these cars, turbo seals. The "solution" besides rebuilding, is to use a thicker oil which takes up the tolerances between moving parts. But oil does need to circulate around moving parts, particularly on startup where most engine wear occurs. Oil is at it's thickest here, so this is where a 10w is a nice balance for an RB engine.

If you're confused about the oil thing Harey, read and read and read this thread - it's lengthy but there's a bit of consensus towards the end.

http://www.skylinesaustralia.com/forums/Go...&start=1760

llama_au Grand Master

llama_au

Posted
Posted
thought you only blow smoke due to the car running rich...is it a different smoke you blow with bad oil?

I did type something earlier but lost it when my internet crashed.

Black Smoke = Unburnt Fuel, not too bad

Blue-White Smoke = Oil, bad. Worn rings, valve stem seals or blown turbo.

White Smoke = Water, bad. Blown head gasket.

Harey Veteran

Harey

Posted
Posted
That's smoke from unburnt fuel when the car is running rich. Yes, it is a different when you burn oil, and it's caused by worn seals/tolerances...e.g. piston rings or more commonly in these cars, turbo seals. The "solution" besides rebuilding, is to use a thicker oil which takes up the tolerances between moving parts. But oil does need to circulate around moving parts, particularly on startup where most engine wear occurs. Oil is at it's thickest here, so this is where a 10w is a nice balance for an RB engine.

If you're confused about the oil thing Harey, read and read and read this thread - it's lengthy but there's a bit of consensus towards the end.

http://www.skylinesaustralia.com/forums/Go...&start=1760

More confused that some people strongly recommend 10W40 and others 10W60. Seems like a big difference to me!

VSPECT Mentor

VSPECT

Posted
Posted
More confused that some people strongly recommend 10W40 and others 10W60. Seems like a big difference to me!

have you spoken to your mechanic? talk to him and listen to him...thats what i am doing...peace of mind and you can trust they know what they talking about....everyone will have different opinion but oil is oil and if your car runs good with the one you using stick to that...thats what i would do.... :)

Birds Grand Master

Birds

Posted
Posted

Most mechanics don't know a great deal about the finer points of oil. Well from my experience working in the industry, most get it very wrong and tend to use only the oils they have in stock (most mechanics keep 2-3 engine oils at the most) :)

But there isn't really such a thing as a bad oil, only a better performing or worse performing oil for your application. Thus what your mechanic recommends may not be perfect for you if he/she has never tried a different oil in your vehicle.

But I do echo what Harsh says in the latter...try a few different oils and then settle upon the one you feel is doing the best job, you won't kill your engine by doing this. 10w40 is a good place to start in an RB.

VSPECT Mentor

VSPECT

Posted
Posted
Most mechanics don't know a great deal about the finer points of oil. Well from my experience working in the industry, most get it very wrong and tend to use only the oils they have in stock (most mechanics keep 2-3 engine oils at the most) :(

But there isn't really such a thing as a bad oil, only a better performing or worse performing oil for your application. Thus what your mechanic recommends may not be perfect for you if he/she has never tried a different oil in your vehicle.

But I do echo what Harsh says in the latter...try a few different oils and then settle upon the one you feel is doing the best job, you won't kill your engine by doing this. 10w40 is a good place to start in an RB.

YAY!!! i was right in something :)

Panko Collaborator

Panko

Posted
Posted

Thinner oil is better for turbo(s) as they are less likely to dried up and clog up inside the turbo and associated hose that running inside and out from turbo(s). so yeah I use Mobil 1 fully synthetic. Won't cost as much as Motul 300V.

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